# kartikay

Brent@GMATPrepNow posted a reply to Is x > 0 ? (1) |x+3| < 4 (2) |x-3| < 4 in the Data Sufficiency forum
“When solving inequalities involving ABSOLUTE VALUE, there are 2 things you need to know: Rule #1: If |something| < k, then –k < something < k Rule #2: If |something| > k, then EITHER something > k OR something < -k Target question: Is x > 0 ? Statement 1: |x+3| < ...”
47 minutes ago
Brent@GMATPrepNow posted a reply to In the xy-plane, what is the y-intercept of line l? in the Data Sufficiency forum
“Target question: What is the y-intercept of line L? IMPORTANT: When I scan the two statements, I see that they are strongly related. If the x-intercept is -1/3 (as per statement 2), the slope of the line is GUARANTEED to be 3 times its y-intercept (as per statement 1). Here''s why... ...”
Today
Brent@GMATPrepNow posted a reply to At garage sale, all of the prices of the items sold were in the Problem Solving forum
“The price of the radio was the 15th highest price So, there were 14 items that were more expensive than the radio. In other words, if we listed all of the prices in ascending order, we''d get something like: ........... radio, X, X, X, X, X, X, X, X, X, X, X, X, X, X The price of the radio ...”
Today
Brent@GMATPrepNow posted a reply to A certain company charges $6 per package to ship packages in the Problem Solving forum “Let x = the weight of the package (in pounds) So, the shipping cost =$6 + 2x We''re told the shipping cost is $38. So, we can write: 6 + 2x = 38 Subtract 6 from both sides: 2x = 32 Solve: x = 32/2 = 16 Answer: A Cheers, Brent” Today Brent@GMATPrepNow posted a reply to Is x/y>1? in the Data Sufficiency forum “Target question: Is x/y > 1? Statement 1: x > y Let''s TEST some values. There are several values of x and y that satisfy statement 1. Here are two: Case a: x = 3 and y = 1. In this case, x/y = 3/1 = 3. So, the answer to the target question is YES, x/y IS greater than 1 Case b: x = ...” Today Brent@GMATPrepNow posted a reply to How many 4-digit numbers greater than 3,000 have the digits: in the Problem Solving forum “Take the task of creating 4-digit numbers and break it into stages. We’ll begin with the most restrictive stage. Stage 1: Select the first digit (to go in the thousands place) Since the 4-digit number must be GREATER THAN 3000, the first digit must be greater than or equal to 3 This means ...” Today Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum “Shortcut for quickly dividing by 5 in your head Video: https://www.youtube.com/watch?v=fK29jTSJOi8 Cheers, Brent” Yesterday Brent@GMATPrepNow posted a reply to At a certain university, the ratio of the number of teaching in the Problem Solving forum “We can solve this using equivalent ratios We''re comparing teaching assistants/number of students Let x = number of students possible We can write: 5/x = 3/80 Cross multiply to get: 3x = (5)(80) Simplify: 3x = 400 Solve: x = 400/3 = 133 1/3 = 133.3333 Since 134 students would exceed ...” Yesterday Brent@GMATPrepNow posted a reply to Automobile A is traveling at two-thirds the speed that in the Data Sufficiency forum “ Given: Automobile A is traveling at two-thirds the speed that Automobile B is traveling. Let A = Car A''s speed Let B = Car B''s speed So, we can write: A = (2/3)B Target question: What is the value of A? Statement 1: If both automobiles increased their speed by 10 miles per hour, ...” Yesterday Brent@GMATPrepNow posted a reply to If every boy in a kindergarten class buys a soda and every g in the Problem Solving forum “Let B = # of boys in kindergarten Let G = # of girls in kindergarten Let J = price (in CENTS) of ONE juice box Let S = price (in CENTS) of ONE soda If every boy in a kindergarten class buys a soda and every girl in the same class buys a juice box, the class will spend 1¢ less in total than it ...” December 17, 2018 Brent@GMATPrepNow posted a reply to Sanjana jogged uphill for a while at an average speed of 3 m in the Problem Solving forum “You could also try testing the answer choices. Cheers, Brent” December 17, 2018 Brent@GMATPrepNow posted a reply to If 3x + 12 = 21, then x + 4 = A. 3 B. 4 C. 5 D. 7 E. 9 in the Problem Solving forum “One option is to first solve the equation, 3x + 12 = 21, for x, and then determine the value of x+4. Alternatively, we can factor the left side to get: 3(x + 4) = 21 Now divide both sides by 3 to get: x + 4 = 7 Answer: D Cheers, Brent” December 17, 2018 Brent@GMATPrepNow posted a reply to If a, b & c are integers, is abc odd? in the Data Sufficiency forum “Some important rules: #1. (ODD)(ODD) = ODD #2. (ODD)(EVEN) = EVEN #3. (EVEN)(EVEN) = EVEN Given: a, b & c are integers Target question: Is abc odd? Statement 1: ab is odd This tells us that a and b are both odd. However, we have no information about c. Consider these two ...” December 17, 2018 Brent@GMATPrepNow posted a reply to In the coordinate plane, the y-intercept of the line k is eq in the Problem Solving forum “One approach is to choose some values that meet the given information. In the coordinate plane, the y-intercept of the line k is equal to twice its slope. Okay, so let''s say the y-intercept of line k is 6. We get: https://i.imgur.com/qJ5GeRQ.png Since the y-intercept (6) is TWICE the ...” December 17, 2018 Brent@GMATPrepNow posted a reply to Sanjana jogged uphill for a while at an average speed of 3 m in the Problem Solving forum “Let''s start with a "Word Equation" (distance traveled uphill) + (distance traveled downhill) = TOTAL DISTANCE Let t = the time spent jogging UPHILL (in hours) The total travel time = 40 minutes = 2/3 HOURS So, 2/3 - t = the time spent jogging DOWNHILL (in hours) Distance = ...” December 16, 2018 Brent@GMATPrepNow posted a reply to If one manual weighs 400 grams, how many kilograms does a in the Problem Solving forum “Since the answer choices are VERY SPREAD APART, we can be quite aggressive with our ESTIMATION. (400 grams)(50 manuals) = 20,000 grams = 20 KILOgrams So, the answer is approximately 20 Answer: C Cheers, Brent” December 16, 2018 Brent@GMATPrepNow posted a reply to Madge paid A dollars for R bananas. Dean paid B dollars for in the Data Sufficiency forum “ Given: Madge paid A dollars for R bananas. Dean paid B dollars for S bananas. Target question: Which one of them paid a higher price-per-banana? Statement 1: B > A This tells us that Dean PAID more than Madge paid. However, we don''t know HOW MANY bananas each person bought. ...” December 15, 2018 Brent@GMATPrepNow posted a reply to Jason's salary and Karen's salary were each p percent in the Data Sufficiency forum “Target question: What is the value of p? Given: Jason''s salary and Karen''s salary were each p percent greater in 1998 than in 1995. IMPORTANT: If my 1998 salary is p percent greater than my 1995 salary, then: 1998 salary = (1 + p/100)(1995 salary) For example, if my 1998 salary is 7 percent ...” December 15, 2018 Brent@GMATPrepNow posted a reply to If w + 2x = 150, 2w + 3y = 100, and x + 3z = 50, what is the in the Problem Solving forum “GIVEN: w + 2x = 150 2w + 3y = 100 x + 3z = 50 If we add all 3 equations, we get: 3w + 3x + 3y + 3z = 300 Divide both sides by 3 to get: w + x + y + z = 100 Answer: D Cheers, Brent” December 15, 2018 Brent@GMATPrepNow posted a reply to If A is the center of the circle shown above and AB = BC in the Problem Solving forum “First recognize that all radii (indicated with BLUE lines) have equal length https://i.imgur.com/iz8ur0Z.png Since BC and CD are both equal to the radius AB, we can see that all BLUE lines have equal length https://i.imgur.com/mF0UxTp.png This means the 2 blue triangles are EQUILATERAL ...” December 13, 2018 Brent@GMATPrepNow posted a reply to If m and n are positive integers, is mn an even number? in the Data Sufficiency forum “Some important rules: #1. ODD +/- ODD = EVEN #2. ODD +/- EVEN = ODD #3. EVEN +/- EVEN = EVEN #4. (ODD)(ODD) = ODD #5. (ODD)(EVEN) = EVEN #6. (EVEN)(EVEN) = EVEN Target question: Is mn an even number? Given: m and n are positive integers Statement 1: m/n is an even number. ...” December 13, 2018 Brent@GMATPrepNow posted a reply to What distance did Jane travel? in the Data Sufficiency forum “Target question: What distance did Jane travel? Statement 1: Bill traveled 40 miles in 40 minutes. No info about Jane Statement 1 is NOT SUFFICIENT Statement 2: Jane traveled at the same average rate as Bill We don''t know Bill''s speed (rate) Statement 2 is NOT SUFFICIENT ...” December 13, 2018 Brent@GMATPrepNow posted a reply to If Mike buys a biclycle and a helmet for a total cost of in the Data Sufficiency forum “Target question: How much does the helmet cost? Given: bicycle + helmet =$315 Statement 1: The bicycle costs twice as much as the helmet. Let x = cost of helmet So, 2x = cost of bicycle Since the total cost is $315, we can write: x + 2x = 315 Simplify: 3x = 315 Solve: x = 315/3 = ...” December 13, 2018 Brent@GMATPrepNow posted a reply to In isosceles triangle DEF, what is the measure of angle E? in the Data Sufficiency forum “Target question: What is the measure of ∠E? Given: Triangle DEF is an ISOSCELES triangle This tells us that there are 2 equal angles Statement 1: ∠D measures 42 degrees Here it''s hard to tell whether there''s a second 42-degree angle or whether the other two angles are different. ...” December 12, 2018 Brent@GMATPrepNow posted a reply to Ramon wants to cut a rectangular board into identical square in the Problem Solving forum “If we aren''t wasting any wood, the length and width must be divisible by one side of the square So, this question is a clever way of asking us what the greatest common divisor (GCD) of 18 and 30 The GCD of 18 and 30 is 6, so if we cut squares that are 6 x 6, then we won''t waste any wood. We ...” December 12, 2018 Brent@GMATPrepNow posted a reply to How many perfect squares lie between 2^4 and 2^8, inclusive? in the Problem Solving forum “First rewrite 2^4 and 2^8 as SQUARES of integers (aka perfect squares) 2^4 = (2²)² = 4² 2^8 = (2^4)² = 16² So, we want to find the number of perfect squares FROM 4² to 16² inclusive Let''s list them: 4², 5², 6², 7², 8², 9², 10², 11², 12², 13², 14², 15², and 16² There are ...” December 12, 2018 Brent@GMATPrepNow posted a reply to If 5x + 3y = 17, what is the value of x? in the Data Sufficiency forum “Target question: What is the value of x? Given: 5x + 3y = 17 Statement 1: x is a positive integer Let''s TEST some values. There are several values of x and y that satisfy statement 1. Here are two: Case a: x = 1 and y = 4 (these values satisfy the given equation, 5x + 3y = 17). In ...” December 12, 2018 Brent@GMATPrepNow posted a reply to How many integers between 324,700 and 458,600 have tens in the Problem Solving forum “We want to determine how many integers end in 13 For example, 324713, 324813, 324913, 325013, . . . etc. Recognize that, for every 100 consecutive integers, only 1 will end in 13. There are 133,900 integers between 324,700 and 458,600 (since 458,600 - 324,700 = 133,900) Of those 133,900 ...” December 11, 2018 Brent@GMATPrepNow posted a reply to The quadrilateral ABCD is a square with sides of length 12. in the Problem Solving forum “This question could take a while to answer (especially if you don''t know where to begin! :-). Fortunately, we can take advantage of an IMPORTANT feature about geometric diagrams on the GMAT: The diagrams in GMAT problem solving questions are DRAWN TO SCALE unless stated otherwise. We have ...” December 11, 2018 Brent@GMATPrepNow posted a reply to A palindrome is a number that reads the same forward and in the Problem Solving forum “Take the task of building palindromes and break it into stages. Stage 1: Select the ten-thousands digit We can choose 1, 2, or 3 So, we can complete stage 1 in 3 ways Stage 2: Select the thousands digit We can choose 1, 2, or 3 So, we can complete stage 2 in 3 ways Stage 3: Select ...” December 11, 2018 Brent@GMATPrepNow posted a reply to This year, a woman has a lucrative one-year position. During in the Problem Solving forum “Let T = the woman''s total salary for the year During this year, she will give a fraction f of her salary to her husband, a private investor, to invest and they will live this year on the remainder. So, the amount SAVED (and then given to huspand)= fT This means the amount SPENT = T - fT ...” December 11, 2018 Brent@GMATPrepNow posted a reply to A frog is climbing a greasy pole. The frog can climb 2 in the Problem Solving forum “Let''s solve this by making table Time elapsed | height 1 hours | 4 cm 2 hours | 8 cm REST (slide) 2.5 hours | 7 cm 3.5 hours | 11 cm 4.5 hours | 15 cm REST (slide) 5 hours | 14 cm 6 hours | 18 cm 7 hours | 22 cm REST (slide) 7.5 hours | 21 cm 8.5 hours | 25 cm 9.5 hours | 29 cm ...” December 11, 2018 Brent@GMATPrepNow posted a reply to Oil, vinegar, and water are mixed in a 3 to 2 to 1 ratio to in the Problem Solving forum “GIVEN: oil: vinegar : water = 3 : 2 : 1 Let''s first try to use ALL 8 cups of oil Take 3 : 2 : 1 and multiply all 3 parts by 8/3 to get the EQUIVALENT ratio 8 : 16/3 : 8/3 Simplify to get: 8 : 5 1/3 : 2 2/3 So, in this case, the dressing is comprised of 8 cups of oil, 5 1/3 cups of vinegar, ...” December 10, 2018 Brent@GMATPrepNow posted a reply to Line DB divides Rectangle ABCD into two equal triangles. Is in the Data Sufficiency forum “IF all 4 sides of the rectangle have EQUAL length (i.e,, the shape is a square), then the diagonal will create two 45-45-90 right triangles. However, if the sides are not all the same length, the resulting triangles will NOT be 45-45-90 right triangles. Cheers, Brent” December 10, 2018 Brent@GMATPrepNow posted a reply to A father distributed his total wealth to his two sons. How in the Data Sufficiency forum “ Given: A father distributed his total wealth to his two sons. Target question: How much wealth did the father have? Statement 1: The elder son received 3/5 of the wealth. Without any dollar values, there''s no way to answer the target question with certainty. So, statement 1 is NOT ...” December 10, 2018 Brent@GMATPrepNow posted a reply to At what speed was Erik running when he was at the halfway po in the Data Sufficiency forum “IMPORTANT: The two statements essentially provide the exact same information. If it took Erik 2 hours to travel 10 miles, we can conclude that his average speed was 5 miles per hour. When the two statements provide the same information in a Data Sufficiency question, the correct answer must be ...” December 10, 2018 Brent@GMATPrepNow posted a reply to [x] is the greatest integer less than or equal to x. What is in the Data Sufficiency forum “Here are a few similar questions to practice with: - https://www.beatthegmat.com/if-is-the-greatest-integer-less-than-or-equal-to-x-what-t302459.html - https://www.beatthegmat.com/g-x-is-the-greatest-integer-less-than-or-equal-to-x-t298237.html - ...” December 10, 2018 Brent@GMATPrepNow posted a reply to When 6 is multiplied by x, the result is the same as when x in the Problem Solving forum “When 6 is multiplied by x, the result is the same as when x is added to 9 In other words: 6x = 9 + x Subtract x from both sides: 5x = 9 Divide both sides by 5 to get: x = 9/5 Answer: E Cheers, Brent” December 9, 2018 Brent@GMATPrepNow posted a reply to Three photographers, Lisa, Mike and Norm, take photos of a w in the Problem Solving forum “We can also solve the question using 1 variable Norms photos number 10 more than twice the number of Lisa''s photos Let x = the number of photographs that Lisa took. So, 2x + 10 = the number of photographs that Norm took. The total of Lisa and Mikes photos is 50 less than the sum of ...” December 9, 2018 Brent@GMATPrepNow posted a reply to At a certain factory, each employee working the second shift in the Problem Solving forum “Let''s assign a "nice" value to the number of widgets made by ONE employee. We''ll also assign a nice value to the number of employees on each shift. At a certain factory, each employee working the SECOND shift produced 2/3 as many widgets as each employee working the FIRST shift. ...” December 9, 2018 Brent@GMATPrepNow posted a reply to If two of the four expressions x+y, x+5y, x-y, and 5x-y are in the Problem Solving forum “Okay, first recognize that x² - (by)² is a DIFFERENCE OF SQUARES. Here are some examples of differences of squares: x² - 25y² 4x² - 9y² 49m² - 100k² In general, we can factor differences of squares as follows: a² - b² = (a-b)(a+b) So . . . x² - 25y² = (x+5y)(x-5y) 4x² - ...” December 8, 2018 Brent@GMATPrepNow posted a new topic called CHALLENGE: What is the value of k? in the Data Sufficiency forum “What is the value of k? $$(1) k^2-5k-66=0$$ $$(2) \frac{2k}{k^2+5k}=\frac{1}{8}$$ Source: www.gmatprepnow.com Answer: B Estimated difficulty level: 600-650” December 7, 2018 Brent@GMATPrepNow posted a reply to Circle question help in the Problem Solving forum “We''ll begin by arbitrarily placing point A somewhere on the circumference. https://i.imgur.com/hRHtq4o.png So, we want to know the probability that a randomly-placed point B will yield a chord AB that is at least 2 cm long. So, let''s first find a location for point B that creates a chord ...” December 7, 2018 Brent@GMATPrepNow posted a reply to Let C be defined as the sum of all prime numbers between in the Problem Solving forum “C = 2 + 3 + 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29 = 129 So, C/3 = 129/3 = 43 Answer: E Cheers, Brent” December 7, 2018 Brent@GMATPrepNow posted a reply to 2k years ago Frank was 3k years old. In k years Frank's age, in the Problem Solving forum “These kinds of questions (Variables in the Answer Choices - VIACs) can be answered algebraically or using the input-output approach. Mitch has solved the question using the input-output approach, so let''s use the algebraic approach. 2k years ago Frank was 3k years old. We''re given Frank''s ...” December 7, 2018 Brent@GMATPrepNow posted a reply to In a 200 member association consisting of men and women, exa in the Problem Solving forum “In order to minimize the number of homeowners, we must MAXIMIZE the number of men in the group, since the proportion of male homeowners (20%) is less than the proportion of female homeowners (25%) So, let''s see what happens if there are 199 men and 1 woman. If 20% (aka 1/5) of the men are ...” December 6, 2018 Brent@GMATPrepNow posted a reply to If all of the telephone extensions in a certain company must in the Problem Solving forum “NOTE: Always SCAN the answer choices before performing any calculations. Here, we notice that the answer choices are pretty small, so if we don''t come up a full solution, we should consider LISTING AND COUNTING We get the following extensions: 1236 1326 1362 1632 2136 2316 3126 3162 ...” December 6, 2018 Brent@GMATPrepNow posted a reply to If all of the telephone extensions in a certain company must in the Problem Solving forum “Take the task of arranging the 4 digits and break it into stages. We’ll begin with the most restrictive stage. Stage 1: Select the digit in the units position Since the 4-digit extension must be EVEN, the unit digit must be either 2 or 6 So, we can complete stage 1 in 2 ways Stage ...” December 6, 2018 Brent@GMATPrepNow posted a reply to What was the revenue that a theater received from the sale in the Data Sufficiency forum “Target question: What was the revenue that a theater received from the sale of 400 tickets Jump straight to . . . Statements 1 and 2 combined The combined statements tell us that 100 tickets sold for the full price of$25 each. The remaining 300 tickets were sold at some reduced price. ...”
December 6, 2018
Brent@GMATPrepNow posted a reply to A certain high school offers two foreign languages, Spanish in the Problem Solving forum
“Another approach is to use the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it (aka overlapping sets questions). Here, we have a population of students, and the two characteristics are: - ...”
December 6, 2018
Brent@GMATPrepNow posted a reply to In year x, it rained on 40% of all Mondays and 20% of all in the Data Sufficiency forum
“In any given year, there will be 52 or 53 Mondays, 52 or 53 Tuesdays, etc. So, it''s impossible to say that it rained on 40% of all Mondays or 20% of all Tuesdays, etc. For example, if there are 52 Mondays, then 40% of 52 = 20.8, which means that it rained on 20.8 days (impossible). Cheers, ...”
December 6, 2018
Brent@GMATPrepNow posted a reply to Three men sit at a table. One dollar is placed in front of in the Problem Solving forum
“Let''s see what happens if a man waits until the last (5th) round to take the money. Round #1: $1 placed in front of the man (but he doesn''t take it) Round #2: Now,$2 placed in front of the man (but he doesn''t take it) Round #3: Now, $4 placed in front of the man (but he doesn''t take it) ...” December 5, 2018 Brent@GMATPrepNow posted a reply to If a, b, and c are positive integers such that a < b < in the Data Sufficiency forum “Target question: Is a% of b% of c an integer? This is a great candidate for rephrasing the target question. Aside: We have a free video with tips on rephrasing the target question: a% of b% of c is the same as (a/100)(b/100)(c), which equals abc/10,000 So, we can rephrase the target ...” December 5, 2018 Brent@GMATPrepNow posted a reply to If w, x, and y are consecutive odd positive integers and w & in the Problem Solving forum “Here''s a 3rd approach: GIVEN: w, x, and y are consecutive odd positive integers and w < x < y Since consecutive odd integers go up by 2, we can write: x = w + 2, and y = w + 2 + 2 = w + 4 So, y - x - w = (w + 4) - (w + 2) - w = w + 4 - w - 2 - w = 2 - w Since w is an ODD integer, ...” December 5, 2018 Brent@GMATPrepNow posted a reply to What is the difference between the number of three-member in the Problem Solving forum “The number of three-member committees that can be formed from a group of nine members Since the order in which we select the 3 people does not matter, we can use combinations. We can choose 3 people from 9 people in 9C3 ways 9C3 = (9)(8)(7)/(3)(2)(1) = 84 three-member committees The total ...” December 5, 2018 Brent@GMATPrepNow posted a reply to All the 7 books of the fictional character series Horry in the Problem Solving forum “At$8 per book, the 8 books SHOULD have cost $64 (8 x$8 = $64) However, Harry bought the 8 books for$60 So, the amount Harry saved = $64 -$60 = $4 What is savings percentage for Harry, who bought the whole set together? Percent savings = 100(amount saved)/(original price) = 100(4)/64 = ...” December 5, 2018 Brent@GMATPrepNow posted a reply to Charlie takes 2.5 hours to fly from Los Angeles to Mexico Ci in the Problem Solving forum “Average speed = (total distance traveled)/(total travel time) So, Average speed = 1200/2.5 = 2400/5 = 4800/10 = 480 mph Answer: D Cheers, Brent” December 4, 2018 Brent@GMATPrepNow posted a reply to In her position as a real estate agent, Sarah receives a bon in the Problem Solving forum “Last week, Sarah earned a$4,000 bonus, which decreased her average bonus amount to $4800. This represents a decrease of 4%. Let x = OLD average bonus amount We can write: x - 0.04x =$4800 Simplify: 0.96x = $4800 Solve: x =$4800/(0.96) = $5000 How many sales has Sarah made? Let n = the ...” December 4, 2018 Brent@GMATPrepNow posted a reply to If there are 4 pairs of twins, and a committee will be in the Problem Solving forum “Here''s another approach. Take the task of selecting the 3 committee members and break it into stages. Stage 1: Select the 3 twins from which we will select 1 spouse each. There are 4 sets of twins, and we must select 3 of them. Since the order in which we select the 3 twins does not ...” December 3, 2018 Brent@GMATPrepNow posted a reply to For each of her sales, a saleswoman receives a commission in the Problem Solving forum “Saleswoman receives a commission equal to 20 percent of the first$500 of the total amount of the sale, plus 30 percent of the total amount in excess of $500 If she sold$800, then... Commission = (20 percent of $500) + (30 percent of$300) = $100 +$90 = $190 The saleswoman''s commission ...” December 1, 2018 Brent@GMATPrepNow posted a reply to Portia purchased a laptop for$480, but after checking the in the Problem Solving forum
“Let x = the INTENDED price of the laptop Portia was overcharged by 20% So, x + (20% of x) = the amount Portia paid In other words: x + 0.2x = $480 Simplify: 1.2x = 480 Solve: x = 480/1.2 = 400 So, Portia was SUPPOSED to pay$400, but she actually paid $480 So, Portia was overcharged ...” December 1, 2018 Brent@GMATPrepNow posted a reply to When a certain tree was first planted, it was 4 feet tall in the Problem Solving forum “Height of tree on day 0 = 4 Let d = the height increase each year Height of tree at the end of the 1st year = 4+d Height of tree at the end of the 2nd year = 4+d+d = 4 + 2d Height of tree at the end of the 3rd year = 4+d+d+d = 4 + 3d Height of tree at the end of the 4th year = 4+d+d+d+d = 4 + ...” December 1, 2018 Brent@GMATPrepNow posted a reply to Last Friday a certain shop sold 3/4 of the sweaters in its in the Data Sufficiency forum “ Given: Last Friday a certain shop sold 3/4 of the sweaters in its inventory. Each sweater sold for$20. Target question: What was the total revenue last Friday from the sale of this sweaters? Statement 1: When the shop opened last Friday, there were 160 sweaters in its inventory. 3/4 ...”
November 30, 2018
Brent@GMATPrepNow posted a reply to When running a mile during a recent track meet, Nuria was in the Problem Solving forum
“The long approach is to meticulously convert 11/25 of a minute to seconds, and then ADD that unaccounted time to Nuria''s recorded time (of 5 minutes, 44 seconds) However, when we check the answer choices before performing any calculations (ALWAYS check the answer choices before performing any ...”
November 30, 2018
Brent@GMATPrepNow posted a reply to GMAT PREP CR... why is A wrong? in the Critical Reasoning forum
“A student asked me to answer this question, so here it goes . . . 1) Read the question stem to determine the question type. Tricky! With fill-in-the-blank questions, it''s often difficult to determine the question type. The last sentence reads Unitron is not going to hire department heads ...”
November 29, 2018
Brent@GMATPrepNow posted a reply to New cars leave a car factory in a repeating pattern of red, in the Problem Solving forum
“Let''s examine the pattern. CAR # | color 1 | red 2 | blue 3 | black 4 | gray 5 | red 6 | blue 7 | black 8 | gray 9 | red . . . The pattern REPEATS EVERY 4 CARS. So, we say the pattern has CYCLE 4 Also, notice that every car # that''s divisible by 4 is gray So, let''s find a ...”
November 29, 2018
Brent@GMATPrepNow posted a reply to If each of the two digits X and Y is distinct, is the two di in the Data Sufficiency forum
“Target question: Is the two-digit integer xy prime? Given: Each of the two digits x and y is distinct Statement 1: Each of the digits x and y is the sum of 2 distinct single digit prime numbers. Let''s TEST some values. There are several values of x and y that satisfy statement 1. Here ...”
November 29, 2018
Brent@GMATPrepNow posted a reply to Joan spent $10 to buy at least one piece each of apples and in the Data Sufficiency forum “Target question: How many apples did Joan buy? Given: Joan spent$10 to buy at least one piece each of apples and oranges at a store where each apple cost $2 and each orange cost$1. Since there are only a handful of possible outcomes, we might benefit from quickly listing them: i) Joan ...”
November 29, 2018
Brent@GMATPrepNow posted a reply to If 320 people attended the wedding and 200 attendees drank in the Data Sufficiency forum
“This question is somewhat ambiguous, since it''s hard to say whether "nondrinkers" in statement 1 refers to people who drank neither beer nor wine, or did not drink beer. I''m assuming that it means to not drink beer, so I''ve add that to the question below. One approach is to use ...”
November 28, 2018
Brent@GMATPrepNow posted a reply to Difficult Manhatan Problem in the Problem Solving forum
“Target question: What is the hundreds digit of the product AB? Given: The difference between positive two-digit integer A and the smaller two-digit integer B is twice A‘s units digit Let x = the tens digit of A, and let y = the units digit of A So, the VALUE of A = 10x + y From the ...”
November 28, 2018
Brent@GMATPrepNow posted a reply to If a child is randomly selected from Columbus Elementary in the Data Sufficiency forum
“Target question: What is the probability that the child will be a boy? This is a good candidate for rephrasing the target question. Let G = # of girls in the school Let B = # of boys in the school So, G + B = total number of children in the school So, P(selected child is a boy) = B/(G + B) ...”
November 28, 2018
Brent@GMATPrepNow posted a reply to A club has 10 members. One president and two vice-presidents in the Problem Solving forum
“Take the task of selecting the president and two vice-presidents and break it into stages. Stage 1: Select the president There are 10 people to choose from. So, we can complete stage 1 in 10 ways Stage 2: Select two people to be the vice-presidents Since the order in which we select the ...”
November 28, 2018
Brent@GMATPrepNow posted a reply to On a partly cloudy day, Derek decides to walk back from work in the Problem Solving forum
“Let''s PLUG IN a nice value for the total distance traveled. If Derek''s average speed is 2.8 mph, then let''s say that he traveled a total of 28 miles. At an average rate of 2.8 mph, a 28 mile trip will take 10 hours. Since Derek''s average speed is BETWEEN 2 and 3 mph, we can conclude that ...”
November 28, 2018
Brent@GMATPrepNow posted a reply to The weights of four packages are 1, 3, 5, and 7 pounds, resp in the Problem Solving forum
“That''s MUCH better than my solution!! Cheers, Brent<i class="em em---1"></i>”
November 27, 2018
Brent@GMATPrepNow posted a reply to The weights of four packages are 1, 3, 5, and 7 pounds, resp in the Problem Solving forum
“For each answer choice, if we CAN create the total given weight, then we can ELIMINATE that answer choice. a) 9 = 1 + 3 + 5 ELIMINATE b) 10 = 3 + 7 ELIMINATE c) 12 = 5 + 7 ELIMINATE d) 13 = 1 + 5 + 7 ELIMINATE By the process of elimination, the correct answer is E Cheers, Brent”
November 27, 2018
Brent@GMATPrepNow posted a reply to If 1+2+2^2+... +2^n=2^{n+1}-1, what is the largest prime fac in the Problem Solving forum
“GIVEN: 1 + 2 + 2^2 + ... + 2^n = 2^{n+1} - 1 So, 1 + 2 + 2^2 + ... + 2^7 = 2^{7+1} - 1 = 2^8 - 1 If we recognize that the above expression is a difference of squares, we can factor it to get.... 2^8 - 1 = (2^4 + 1)(2^4 - 1) = (2^4 + 1)(2^2 + 1)(2^2 - 1) = (16 + 1)(4 + 1)(4 - 1) = ...”
November 27, 2018
Brent@GMATPrepNow posted a reply to How many integers from 0 to 50, inclusive, have a remainder in the Problem Solving forum
“When it comes to remainders, we have a nice rule that says: If N divided by D leaves remainder R, then the possible values of N are R, R+D, R+2D, R+3D,. . . etc. For example, if k divided by 5 leaves a remainder of 1, then the possible values of k are: 1, 1+5, 1+(2)(5), 1+(3)(5), ...”
November 27, 2018
Brent@GMATPrepNow posted a reply to Is b even? in the Data Sufficiency forum
“Target question: Is b even? KEY POINT: We are not told that a and b are INTEGERS. As such, we can jump straight to. . . . Statements 1 and 2 combined There are several values of a and b that satisfy BOTH statements. Here are two: Case a: a = 4 and b = 2. Notice that a/b = 4/2 = 2, ...”
November 27, 2018
Brent@GMATPrepNow posted a reply to In the rectangular coordinate system shown above, does the in the Data Sufficiency forum
“Target question: Does line k intersect quadrant II? Statement 1: The slope of k is -1/6 Here are a few lines with slope -1/6 https://i.imgur.com/1p6USLh.png KEY CONCEPT: As we travel from right to left along a line with slope -1/6, we keep moving up. So, at some point, the line will ...”
November 27, 2018
Brent@GMATPrepNow posted a reply to A certain recipe calls for 2 cups of sugar and 3 1/2 cups of in the Problem Solving forum
“Judging from the OA, I''ve added some key text below A certain recipe calls for 2 cups of sugar and 3 1/2 cups of flour So sugar/flour = 2/3.5 Check answer choices . . . . not there. Looks like we need to create a ratio that''s EQUIVALENT to 2/3.5 Multiply top and bottom by 2 to get ...”
November 27, 2018
Brent@GMATPrepNow posted a reply to When the positive integer x is divided by 6, the remainder in the Problem Solving forum
“Good catch - thanks Fabio! I''ve edited my response accordingly. Cheers, Brent”
November 26, 2018
Brent@GMATPrepNow posted a reply to In a certain state, gasoline stations compute the price per in the Problem Solving forum
“In a certain state, gasoline stations compute the price per gallon "p", in dollars, charged at the pump by adding a 4 percent sales tax to the dealer''s price per gallon "d", in dollars . . . We can write: p = d + 4% of d = d + 0.04d = 1.04d So, we have: p = 1.04d . . . ...”
November 26, 2018
Brent@GMATPrepNow posted a reply to When the positive integer x is divided by 6, the remainder in the Problem Solving forum
“APPROACH#2 When the positive integer x is divided by 6, the remainder is 4 In other words, x is 4 greater than some multiple of 6 We can write: x = 6k + 4, where k is an integer If x = 6k + 4, we can also write: x = 6k + 3 + 1 Factor to get: x = 3(2k + 1) + 1 Since 2k+1 must be an integer, ...”
November 26, 2018
Brent@GMATPrepNow posted a reply to When the positive integer x is divided by 6, the remainder in the Problem Solving forum
“----ASIDE------------------- When it comes to remainders, we have a nice rule that says: If N divided by D leaves remainder R, then the possible values of N are R, R+D, R+2D, R+3D,. . . etc. For example, if k divided by 5 leaves a remainder of 1, then the possible values of k are: 1, ...”
November 26, 2018
Brent@GMATPrepNow posted a reply to A chili recipe calls for the final mixture to consist of 1/2 in the Problem Solving forum
“A chili recipe calls for the final mixture to consist of 1/2 meat and 1/3 beans, with the remainder an even mixture of sauce and various spices Let''s see what fraction of the final mixture is sauce and various spices 1/2 + 1/3 = 3/6 + 2/6 = 5/6 If 5/6 of the mixture is meat and beans, then the ...”
November 26, 2018
Brent@GMATPrepNow posted a reply to A store sells only two types of shirts, branded and in the Data Sufficiency forum
“ Given: All the branded shirts are priced at $60 per unit and all the non-branded shirts are priced at$20 per unit. On a certain day, the store sold a total of 30 shirts. Let B = # of branded shirts sold Let N = # of non-branded shirts sold If a TOTAL of 30 shirts were sold, we can write: N + ...”
November 26, 2018
Brent@GMATPrepNow posted a reply to Of the 4,800 voters who voted for or against Resolution K, in the Data Sufficiency forum
“Target question: What was the total number of female voters who voted for Resolution K? When solving Data Sufficiency questions, it''s important that you don''t perform more calculations than are necessary. So, for this question, we need only determine whether or not we have sufficient ...”
November 26, 2018
Brent@GMATPrepNow posted a reply to If x and y are nonnegative integers, what is the value of y? in the Data Sufficiency forum
“The above solutions are great. I just wanted to add that whenever you''re told that a value is non-negative on the GMAT, you should be sure to consider what happens when that value equals zero Keep in mind that, if the test-makers wanted to restrict a value to POSITIVE values only, then they''d ...”
November 25, 2018
Brent@GMATPrepNow posted a reply to If n is the smallest integer such that 432 times n is the in the Problem Solving forum
“IMPORTANT CONCEPT: The prime factorization of a perfect square (the square of an integer) will have an even number of each prime For example: 400 is a perfect square. 400 = 2x2x2x2x5x5. Here, we have four 2''s and two 5''s This should make sense, because the even numbers allow us to split the ...”
November 25, 2018
Brent@GMATPrepNow posted a reply to Set P {a, b, c, d, e, f, g} Set Q {a, b, c, d, e, f} If a, b in the Problem Solving forum
“The key here is MUST be true. So, if we can find an example in which a statement is NOT true, then we can ELIMINATE it. We have: Set P {a, b, c, d, e, f, g} Set Q {a, b, c, d, e, f} I''ll make the extra value red so it''s easier to compare the two sets So, the sets COULD be: Set P {1, 2, ...”
November 25, 2018
Brent@GMATPrepNow posted a reply to Every object in a box is either a sphere or a cube, and ever in the Data Sufficiency forum
“Target question: How many objects are in the box? Given: Every object in a box is either a sphere or a cube, and every object in the box is either red or green. We can solve this using the Double Matrix Method. This technique can be used for most questions featuring a population in which ...”
November 25, 2018
Brent@GMATPrepNow posted a reply to Last month, a florist gave 7 percent of her sales revenue to in the Problem Solving forum
“Choose a "nice" number for the sales revenue Let $100 = LAST MONTH''s revenue So,$120 = THIS MONTH''s revenue (since sales were up 20 percent from last month) LAST month, a florist gave 7 percent of her sales revenue to her employees in bonuses So, bonuses = 7% of $100 =$7 ...”
November 23, 2018
Brent@GMATPrepNow posted a reply to In a plane, there are two parallel lines. One line has 5 in the Problem Solving forum
“There are two ways in which we can create a triangle. #1) Select 2 points from the 5-point line and select 1 point from the 4-point line. #2) Select 2 points from the 4-point line and select 1 point from the 5-point line. #1) Select 2 points from the 5-point line and select 1 point from the ...”
November 23, 2018
Brent@GMATPrepNow posted a reply to GMAT PREP KAPLAN VIDEO in the The 60-Day GMAT Study Guide forum
“Thanks for the heads up. This video should serve as a replacement: https://www.gmatprepnow.com/module/general-gmat-strategies/video/1250 Cheers, Brent”
November 23, 2018
Brent@GMATPrepNow posted a reply to Alan and Peter are cycling at different constant rates on a in the Data Sufficiency forum
“ Given: Alan is NOW 3 miles ahead of Peter Target question: How many minutes from now will Peter be 1 mile ahead of Alan? Statement 1: ONE HOUR AGO, Alan was 7 miles ahead of Peter. Alan is NOW 3 miles ahead of Peter So, in one hour, the GAP between Alan and Peter decreased by 4 miles ...”
November 23, 2018
Brent@GMATPrepNow posted a reply to List M consists of 50 decimals, each of which has a value be in the Problem Solving forum
“Let''s examine the EXTREME CASES S - T = x percent of T So, S - T = (x/100)T Divide both sides by to get: (S - T)/T = x/100 Multiply both sides by 100 to get: x = 100(S - T)/T First, we we''ll MINIMIZE the value of x by minimizing the value of S - T and maximizing the value of T. This ...”
November 23, 2018
Brent@GMATPrepNow posted a reply to R and S can complete a certain job in 6 and 4 days respectiv in the Problem Solving forum
“Let''s assign a "nice" value to the job, a value that works well with the given values (6 days and 4 days ). So, let''s say the ENTIRE job is to make 24 widgets R can complete a certain job in 6 days In other words, R can make 24 widgets in 6 days So, R can make 4 widgets per day ...”
November 23, 2018
Brent@GMATPrepNow posted a reply to A certain telephone company offers two plans, A and B. Under in the Problem Solving forum
“Let x = the duration of the phone call (in minutes) Under plan A, the company charges a total of $0.60 for the first 7 minutes of each call and$0.06 per minute thereafter. So, the TOTAL cost = $0.60 + (x - 7 minutes)($0.06) = 0.60 + (0.06x - 0.42) = 0.06x + 0.18 Under plan B, the company ...”
November 23, 2018
Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“The Something Method for solving certain equations Video: https://www.youtube.com/watch?v=mmTisgtNfTI Cheers, Brent”
November 21, 2018
Brent@GMATPrepNow posted a reply to If m represents the slope of a line in the coordinate geomet in the Data Sufficiency forum
“Target question: Does the line intersect quadrant III? Jump straight to... Statements 1 and 2 combined Here are two scenarios that satisfy BOTH statements: Case a: m = 3 https://i.imgur.com/2SVui9E.png In this case, the answer to the target question is YES, the line DOES intersect ...”
November 21, 2018
Brent@GMATPrepNow posted a reply to In the first year of a pyramid scheme, John convinced y of in the Data Sufficiency forum
“Target question: What was the value of y? Statement 1: The revenue for the website that year was $36,000. First round of "investors": y people paying$30 each = 30y dollars Second round of "investors": y² people paying $15 each = 15y² dollars Total revenue = 15y² + ...” November 21, 2018 Brent@GMATPrepNow posted a reply to Missing day 20 in the The 60-Day GMAT Study Guide forum “Done! Cheers, Brent” November 21, 2018 Brent@GMATPrepNow posted a reply to Luxo paint contains only alcohol and pigment. What is the in the Data Sufficiency forum “Target question: What is the ratio of alcohol to pigment in Luxo paint? Given: Luxo paint contains ONLY alcohol and pigment. Statement 1: Exactly 7 ounces of pigment are contained in a 12-ounce can of Luxo paint. If 7 of the 12 ounces of paint are PIGMENT, then the remaining 5 ounces ...” November 21, 2018 Brent@GMATPrepNow posted a reply to A children's theater sels tickets to a show. Tickets for in the Data Sufficiency forum “ Given: Tickets for children cost$10 and tickets for adults cost $35. Ticket revenues from the last performance were$390 Let A = # of adults in attendance Let C = # of children in attendance So, we can write: 35A + 10C = 390 Since A and C must be POSITIVE INTEGERS, there are not many ...”
November 20, 2018
Brent@GMATPrepNow posted a reply to A number when divided by 4 and 5 leaves remainders 1 and 4 in the Problem Solving forum
“When it comes to remainders, we have a nice rule that says: If N divided by D, leaves remainder R, then the possible values of N are R, R+D, R+2D, R+3D,. . . etc. For example, if k divided by 5 leaves a remainder of 1, then the possible values of k are: 1, 1+5, 1+(2)(5), 1+(3)(5), ...”
November 20, 2018
Brent@GMATPrepNow posted a reply to The number line above represents which of the following in the Problem Solving forum
“We can also solve the question by testing the answer choices Here''s what I mean: The diagram tells us that x= 0 is a solution to the inequality. When we check the answer choices, we see that answer choice D (1 < 2x < 3) does NOT have x = 0 as a solution. When we let x = 0, the ...”
November 19, 2018
Brent@GMATPrepNow posted a reply to If n is an integer between 30 and 50 inclusive, what is the in the Data Sufficiency forum
“Target question: What is the value of n? Given: n is an integer between 30 and 50 inclusive Statement 1: When n is divided by 8, the remainder is 7 ------ASIDE-------------------------------------- When it comes to remainders, we have a nice rule that says: If N divided by D leaves ...”
November 19, 2018
Brent@GMATPrepNow posted a reply to When sold at a 40% discount, a sweater nets the merchant a in the Problem Solving forum
“Let''s work BACKWARDS. Let''s say the WHOLESALE price was $100 the merchant made a net profit of 20% on the wholesale cost (which was$100) So, the merchant sold the sweater for $120 Let M = the markup price on the label (before any discounts). So, 40% less than M =$120 In other ...”
November 19, 2018
Brent@GMATPrepNow posted a reply to Kevin buys beer in bottles and cans. He pays $1.00 for each in the Data Sufficiency forum “Target question: How many bottles of beer did Kevin buy? Given: Kevin pays$1.00 for each can of beer and $1.50 for each bottle of beer. Kevin buys a total of 15 bottles and cans of beer Let C = the NUMBER of Cans that Kevin bought Let B = the NUMBER of Bottles that Kevin bought So, we can ...” November 16, 2018 Brent@GMATPrepNow posted a reply to What is the least possible product of 4 different integers, in the Problem Solving forum “We want values with the greatest MAGNITUDE So (10)(9)(8)(-5) = -3600 Answer: -3600 Answer: B” November 16, 2018 Brent@GMATPrepNow posted a reply to A reatil appliance store priced a video recorder at 20 in the Problem Solving forum “A retail appliance store priced a video recorder at 20 percent above the wholesale cost of$200 20% of $200 =$40 So, the retail price = $200 +$40 = $240 If a store employee applied the 10 percent employee discount to the retail price to buy the recorder, how much did the employee pay for the ...” November 16, 2018 Brent@GMATPrepNow posted a reply to Planning is in progress for a fenced, rectangular playground in the Problem Solving forum “It''s a good idea to first try to understand what the graph is telling us. For example, the leftmost point on the curve has the coordinates (10, 340) This tells us that, if the length of the playground is 10 meters, then a total of 340 meters of fencing is required. This makes sense, since we ...” November 16, 2018 Brent@GMATPrepNow posted a reply to When a certain tree was first planted, it was 4 feet tall, in the Problem Solving forum “Height of tree on day 0 = 4 Let d = the height increase each year Height of tree at the end of the 1st year = 4+d Height of tree at the end of the 2nd year = 4+d+d = 4 + 2d Height of tree at the end of the 3rd year = 4+d+d+d = 4 + 3d Height of tree at the end of the 4th year = 4+d+d+d+d = 4 + ...” November 16, 2018 Brent@GMATPrepNow posted a reply to In the rhombus ABCD, the length of diagonal BD is 6 and the in the Problem Solving forum “In a rhombus, the diagonals are perpendicular bisectors. http://i1168.photobucket.com/albums/r500/GMATPrepNow/rhmbs1_zps1nyufj6q.png So, we can add our lengths as follows. http://i1168.photobucket.com/albums/r500/GMATPrepNow/rhmbs2_zpskyv3wwkl.png From here, if we focus on one of the 4 ...” November 16, 2018 Brent@GMATPrepNow posted a reply to If xy is not equal to zero, what is the ratio of x to y? in the Data Sufficiency forum “NOTE: We can write the ratio x:y as a fraction x/y Target question: What is the value of x/y ? Statement 1: 3x = 4y Divide both sides by y to get: 3x/y = 4 Divide both sides by 3 to get: x/y = 4/3 So, the answer to the target question is x/y = 4/3 Since we can answer the target question ...” November 16, 2018 Brent@GMATPrepNow posted a reply to At the Trenchard Oaks apartment complex, a two-bedroom in the Problem Solving forum “A fast and easy approach is to assign a "nice" value to the monthly rent of a ONE-bedroom apartment. Let''s say the rent on a ONE-bedroom apartment is$100 per month A two-bedroom apartment costs 50% more to rent than a one-bedroom apartment 50% of $100 =$50 So, the rent on a ...”
November 15, 2018
Brent@GMATPrepNow posted a reply to If line k in the xy-coordinate plane has the equation Ax + B in the Data Sufficiency forum
“ Given: Line k has the equation Ax + By = C Target question: What is the slope of line k ? This is a good candidate for rephrasing the target question. Let''s take the given equation Ax + By = C and rewrite it in slope y-intercept form, y = mx + b, where m = slope and b = y-intercept ...”
November 15, 2018
Brent@GMATPrepNow posted a reply to What is the ratio of x:y:z? in the Data Sufficiency forum
“Target question: What is the ratio of x:y:z? Statement 1: xy = 14 In information about z Statement 1 is NOT SUFFICIENT Statement 2: yz = 21 In information about x Statement 2 is NOT SUFFICIENT Statements 1 and 2 combined There are several values of x, y and z that satisfy BOTH ...”
November 15, 2018
Brent@GMATPrepNow posted a reply to If xy : yz : zx = 1:2:3, then what is x : y : z ? in the Problem Solving forum
“Let''s focus on pairs of values If xy : yz : zx = 1:2:3, then we know that xy : yz = 1:2 Take xy : yz and divide both sides by y to get the EQUIVALENT ratio x:z This means x:z = 1:2 Check the answer choices... A. 2 : 3 : 6 this answer choice says x:z = 2:6. We need x:z = 1:2 ELIMINATE A ...”
November 15, 2018
Brent@GMATPrepNow posted a reply to Over a four-game stretch, Dennis's bowling scope average 240 in the Problem Solving forum
“In other words, an increase from 240 to 300 represents what kind of percent increase? Percent increase = (100)(new - old)/old = (100)(300 - 240)/240 = (100)(60)/240 = (100)(1/4) = 25% Answer: B Cheers, Brent”
November 15, 2018
Brent@GMATPrepNow posted a reply to The table above shows the distribution of tests scores for a in the Problem Solving forum
“Since we have an ODD number of values, the median will be the MIDDLEMOST value. In other words, if we arrange all 73 values in ASCENDING order, the median will be the 37th value (i.e., 36 values are below and 36 values are above). The table says the first 2 scores in the 50-59 range. So, the 1st ...”
November 15, 2018
Brent@GMATPrepNow posted a reply to # X-Axis Intercepts in the Problem Solving forum
“Let''s find some points that lie on each of the curves. So, for each equation, we''ll find a pair of values (an x-value and a y-value) that satisfy each equation. We''ll do so by plugging in some x-values and calculating the corresponding y-values. Let''s start with x = 0 Plug x = 0 into ...”
November 14, 2018
Brent@GMATPrepNow posted a reply to How many positive two-digit numbers yield a remainder of 1 in the Problem Solving forum
“When it comes to remainders, we have a nice rule that says: If N divided by D leaves remainder R, then the possible values of N are R, R+D, R+2D, R+3D,. . . etc. For example, if k divided by 5 leaves a remainder of 1, then the possible values of k are: 1, 1+5, 1+(2)(5), 1+(3)(5), ...”
November 14, 2018
Brent@GMATPrepNow posted a reply to When Leo imported a certain item, he paid a 7 percent import in the Problem Solving forum
“Here''s a step-by-step algebraic solution. Let T = the TOTAL value of the item. Leo paid a 7% import tax on the portion of the total value of the item in EXCESS of $1000 So, Leo pays tax on the amount that''s GREATER then$1000 So, Leo pays 7% tax on (T - 1000) We can write: import tax = ...”
November 13, 2018
Brent@GMATPrepNow posted a reply to If xy ≠ 0 and x^2+4y^2=4xy, (x+y)/(x-y)=? in the Problem Solving forum
“GIVEN: x² + 4y² = 4xy Subtract 4xy from both sides to get: x² - 4xy + 4y² = 0 Factor left side to get: (x - 2y)(x - 2y) = 0 So, we can conclude that (x - 2y) = 0, which means x = 2y Now take (x+y)/(x-y) and replace x with 2y to get: (x + y)/(x - y) = (2y + y)/(2y - y) = 3y/y = 3 ...”
November 13, 2018
Brent@GMATPrepNow posted a reply to OG #217 question in the Problem Solving forum
“P(selecting a sibling pair) = P(select a junior with a sibling AND select the senior who is that junior''s sibling) = P(select a junior with a sibling) x P(select the senior who is that junior''s siblingx 1/800 = 60/800,000 = 3/40,000 = A Note: P(select a junior with a sibling) = 60/1000, ...”
November 12, 2018
Brent@GMATPrepNow posted a reply to In the figure AB and CD are two diameters of circle. in the Problem Solving forum
“Let''s use some useful circle properties First let''s add a blue line, to divide ∠CEB into 2 angles https://i.imgur.com/xe05QIU.png CD is the DIAMETER of the circle Since ∠CED is an inscribed angle containing (aka "holding") the diameter, we can conclude that ∠CED = 90° ...”
November 12, 2018
Brent@GMATPrepNow posted a reply to Is the tallest child in Class A taller than tallest child in in the Data Sufficiency forum
“Target question: Is the tallest child in Class A is taller than tallest child in Class B? Jump to . . . Statements 1 and 2 COMBINED There are several scenarios that satisfy BOTH statements. Here are two: Case a: Class A heights = {1, 50} and Class B heights = {2, 40}. In this case, the ...”
November 12, 2018
Brent@GMATPrepNow posted a reply to Eight women and two men are available to serve on a in the Problem Solving forum
“When it comes to probability questions involving "at least," it''s best to try using the complement. That is, P(Event A happening) = 1 - P(Event A not happening) So, here we get: P(getting at least 1 man) = 1 - P(not getting at least 1 man) What does it mean to not get at least 1 man? ...”
November 11, 2018
Brent@GMATPrepNow posted a reply to If the positive integer n is greater than 6, what is the in the Data Sufficiency forum
“Here''s a somewhat long approach (but it works!): Target question: What is the remainder when n is divided by 6? Given: Positive integer n is greater than 6 Statement 1: When n is divided by 9, the remainder is 2. ------ASIDE---------------- When it comes to remainders, we have a ...”
November 11, 2018
Brent@GMATPrepNow posted a reply to If x and y are positive integers, what is the remainder when in the Data Sufficiency forum
“Hi Swerve, To avoid ambiguity, you might want to add some spaces or brackets to the original expression. As it stands, 10^x+y could be interpreted as either 10^(x+y) or (10^x) + y Cheers, Brent”
November 11, 2018
Brent@GMATPrepNow posted a reply to If x and y are positive integers such that x = 8y + 12, what in the Data Sufficiency forum
“Target question: What is the greatest common divisor of x and y? Given: x = 8y + 12 Statement 1: x = 12u, where u is an integer. There are several pairs of values that satisfy the given conditions. Here are two: Case a: x=36 and y=3, in which case the GCD of x and y is 3 Case b: x=60 ...”
November 11, 2018
Brent@GMATPrepNow posted a reply to Which of the following is closest to the value of (2^23) in the Problem Solving forum
“(2^23)(5^26) = (2^23)(5^23)(5^3) = (2^23)(5^23)(5^3) = (10^23)(5^3) = (10^23)(125) ≈ (10^23)(100) ≈(10^23)(10^2) ≈10^25 Answer: C Cheers, Brent”
November 11, 2018
Brent@GMATPrepNow posted a reply to A gardener is going to plant 2 red rosebushes and 2 white in the Problem Solving forum
“We can also apply probability rules: P(2 middle bushes are red) = P(1st bush is white AND 2nd bush is red AND 3rd bush is red AND 4th bush is white) = P(1st bush is white) x P(2nd bush is red) x P(3rd bush is red) x P(4th bush is white) = 2/4 x 2/3 x 1/2 x 1/1 = 1/6 = B Cheers, Brent”
November 11, 2018
Brent@GMATPrepNow posted a reply to A gardener is going to plant 2 red rosebushes and 2 white in the Problem Solving forum
“As with many probability questions, we can also solve this using counting techniques. P(2 middle are red) = (# of outcomes with 2 red in middle)/(total number of outcomes) Label the 4 bushes as W1, W2, R1, R2 total number of outcomes We have 4 plants, so we can arrange them in 4! ways = ...”
November 11, 2018
Brent@GMATPrepNow posted a reply to Of the first three dozen cookies baked at a bake shop on a in the Data Sufficiency forum
“ Given: Of the first three dozen (36) cookies baked at a bake shop on a certain day, 1/3 were chocolate chip cookies. 1/2 of the remaining cookies that were baked that day were chocolate chip cookies, 1/3 of 36 = 12. So, 12 chocolate cookies were baked in the first round of baking. Let x = ...”
November 10, 2018
Brent@GMATPrepNow posted a reply to There were 36,000 hardback copies of a certain novel sold in the Problem Solving forum
“From the time the first paperback copy was sold until the last copy of the novel was sold 9 times as many paperback copies as hardback copies were sold Let x = number of hardback copies sold during this time So 9x = number of paperback copies sold during this time So, x + 9x = total number of ...”
November 10, 2018
Brent@GMATPrepNow posted a reply to A box contains 10 balls numbered from 1 to 10 inclusive. If in the Problem Solving forum
“P(Ann and Jane remove same ball) = P(Ann removes ANY ball AND Jane''s ball matches Ann''s ball) = P(Ann removes ANY ball) x P(Jane''s ball matches Ann''s ball) = 1 x 1/10 = 1/10 Answer: D Aside: Once Jane removes her ball (and then replaces it), we have 10 balls, and 1 of them is the one ...”
November 10, 2018
Brent@GMATPrepNow posted a reply to If CD = 6, what is the length of BC? in the Data Sufficiency forum
“Is there an image? Cheers, Brent”
November 9, 2018
Brent@GMATPrepNow posted a reply to Andrew has a certain number of coins in his pocket. He has in the Problem Solving forum
“Let x = number of QUARTERS in pocket So, 0.25x = VALUE of quarters in pocket He has three times as many dimes as quarters So, 3x = number of DIMES in pocket So, 0.10(3x) = 0.3x = VALUE of dimes in pocket He has six times as many nickels as dimes. So, (6)(3x) = number of NICKELS in ...”
November 8, 2018
Brent@GMATPrepNow posted a reply to Challenge: Al, Bob, Cal and Don each own 1 hat. If the 4... in the Problem Solving forum
“I created this question to highlight many students'' tendency to avoid listing and counting as a possible approach. As you''ll see, the approach is probably the fastest approach. P(no one receives his own hat) = (# of outcomes in which no one receives his own hat)/(TOTAL number of outcomes) ...”
November 8, 2018
Brent@GMATPrepNow posted a reply to There are 27 different three-digit integers that can be in the Problem Solving forum
“Yes, great work, Mitch! I thought I''d mention that, once we know the correct answer is a multiple of 222 (which is also a multiple of 3), then the correct answer will be a multiple of 3. Useful property: If a number is a multiple of 3, then the sum of its digits is also a multiple of 3. When we ...”
November 7, 2018
Brent@GMATPrepNow posted a new topic called Challenge: Al, Bob, Cal and Don each own 1 hat. If the 4... in the Problem Solving forum
“Al, Bob, Cal and Don each own 1 hat. If the 4 hats are randomly distributed so that each man receives exactly 1 hat, what is the probability that no one receives his own hat? A) 1/8 B) 1/4 C) 1/3 D) 3/8 E) 1/2 Answer: D Difficulty level: 650 – 700 Source: www.gmatprepnow.com”
November 7, 2018
Brent@GMATPrepNow posted a reply to If x, y and z are non-negative integers such that x < y & in the Problem Solving forum
“I created this question to show that there can be times when the best (i.e., fastest) way to solve a counting question is by listing and counting How do we know when it''s not a bad idea to use listing and counting? The answer choices will tell us (ALWAYS scan the answer choices before ...”
November 7, 2018
Brent@GMATPrepNow posted a reply to How many men are in a certain company's vanpool program? in the Data Sufficiency forum
“Target question: How many men are in a certain company''s vanpool program? Statement 1: The ratio of men to women in the program is 3 to 2. Let''s TEST some values. There are several scenarios that satisfy statement 1. Here are two: Case a: There are 3 men and 2 women in the program. In ...”
November 7, 2018
Brent@GMATPrepNow posted a reply to Speed Time Distance MGMAT in the Problem Solving forum
“GIVEN: When the men start walking, Brian has a 30-mile lead Let B = Brian''s walking speed (in miles per hour) Let A = Ashok''s walking speed (in miles per hour) Since Ashok''s speed is greater than Brian''s speed, the rate at which the gap shrinks = (A - B) miles per hour For example, if A ...”
November 6, 2018
Brent@GMATPrepNow posted a reply to 2019 GMAC Official Guide applicable for 60-Day Study Guide? in the The 60-Day GMAT Study Guide forum
“If you go here (https://www.gmatprepnow.com/content/improvement-chart) and download the Improvement Chart for the OG2016, you''ll see the question breakdown for each topic. This should help. Cheers, Brent”
November 6, 2018
Brent@GMATPrepNow posted a reply to In a certain game, a large bag is filled with blue, green, in the Problem Solving forum
“This question begs for some prime factorization. 88,000 = (2)(2)(2)(2)(2)(2)(5)(5)(5)(11) First, we can see that there must be one (11-point) red chip. Now, what role do these 2''s play? Since there are no 2''s hiding among the 5-point chips or the 11-point chips, the 2''s must be associated ...”
November 6, 2018
Brent@GMATPrepNow posted a reply to [x] is the greatest integer less than or equal x, what is th in the Problem Solving forum
“GIVEN: For example, [3.2] = 3, since 3 is the greatest integer that is less than (or equal) to 3.2 Likewise, [8.7] = 8, since 8 is the greatest integer that is less than (or equal to) 8.7 Now onto the question.... √25 = 5 √36 = 6 √49= 7 √64 = 8 Since √30 is BETWEEN √25 ...”
November 6, 2018
Brent@GMATPrepNow posted a reply to If in k+1 years from now John will be m years old, then how in the Problem Solving forum
“In k+1 years from now John will be m years old So, m - (k + 1) = John''s PRESENT age How old was John t-1 years ago? So, m - (k + 1) - (t - 1) = John''s age (t-1) YEARS AGO Simplify m - (k + 1) - (t - 1) to get: m - k - t Answer: A Cheers, Brent”
November 6, 2018
Brent@GMATPrepNow posted a reply to Pipe A runs 30 liters of water per minute into a pool that in the Problem Solving forum
“Let''s determine the COMBINED RATE of the two pipes Given: Pipe A''s RATE = 30 liters per minute This is equivalent to 1800 liters per HOUR Pipe B fills a third of the pool in 6 hours So, Pipe B fills the ENTIRE pool (3600 liters) in 18 hours Rate = Output/time = 3600/18 = 200 liters ...”
November 6, 2018
Brent@GMATPrepNow posted a new topic called If x, y and z are non-negative integers such that x < y < z, in the Problem Solving forum
“If x, y and z are non-negative integers such that x < y < z, then the equation x + y + z = 11 has how many distinct solutions? A) 5 B) 10 C) 11 D) 22 E) 78 Answer: B Difficulty level: 600-650 Source: www.gmatprepnow.com”
November 5, 2018
Brent@GMATPrepNow posted a reply to Challenge question: Is |1 - 4k| < k? in the Data Sufficiency forum
“Target question: Is |1 - 4k| < k? Statement 1: k > 4x³ This pretty much tells is that k can have ANY value. For example, notice that, if x = -100, then 4x³ = -4,000,000 So, for this value of x, k can be any number greater than -4,000,000 Let''s TEST some values. There are ...”
November 5, 2018
Brent@GMATPrepNow posted a reply to Which sport utility vehicle has a higher list price, the in the Data Sufficiency forum
“Target question: Which sport utility vehicle has a higher list price, the Touristo of the Leisure? Statement 1: The list price of the Leisure is 5/6 the list price of the Touristo. If the Leisure''s price is 5/6 of the Touristo''s price, then the answer to the target question is the Touristo ...”
November 5, 2018
Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“Here''s our video on Range and Standard Deviation https://www.youtube.com/watch?v=FbAlIjw2fwY Cheers, Brent”
November 5, 2018
Brent@GMATPrepNow posted a reply to If xy=-18, is x less than y? in the Data Sufficiency forum
“ Given: xy = -18 Target question: is x less than y? Statement 1: x < 0 In other words, x is NEGATIVE So, our given information (xy = -18) becomes: (NEGATIVE)(y) = -18 In other words: (NEGATIVE)(y) = NEGATIVE This tells us that y is POSITIVE If y is POSITIVE, and x is NEGATIVE, the ...”
November 4, 2018
Brent@GMATPrepNow posted a reply to Challenge #2: If x and y are different positive integers, wh in the Problem Solving forum
“i) When x is divided by y, the remainder is 2x The remainder cannot be greater than the dividend (the number we''re dividing) For example, it CANNOT be the case that 17 divided by 5 leaves a remainder of 34 Statement i can never be true Check the answer choices. . . . ELIMINATE A and D ii) ...”
November 3, 2018
Brent@GMATPrepNow posted a new topic called Challenge question: Is |1 - 4k| < k? in the Data Sufficiency forum
“Is |1 - 4k| < k? (1) k > 4x³ (2) k < 2x – x² - 2 Answer: B Difficulty level: 700+ Source: www.gmatprepnow.com”
November 3, 2018
Brent@GMATPrepNow posted a reply to If the average (arithmetic mean) of p, q, and r is 6, what i in the Data Sufficiency forum
“ Given: The average (arithmetic mean) of p, q, and r is 6 We can write: (p + q + r)/3 = 6 This means: p + q + r = 18 Target question: What is the value of r? Statement 1: p = -r Given: p + q + r = 18 Replace p with -r to get: -r + q + r = 18 Simplify: q = 18 What about the value of ...”
November 2, 2018
Brent@GMATPrepNow posted a reply to Cars J and K are making the trip from City A to City B. in the Problem Solving forum
“Car K travels at a constant speed that is 80% the constant speed of Car J Let''s assign some nice values to the speeds. Let''s say Car J travels 40 miles per hour So, Car K travels 32 miles per hour Car J departs from City A 15 minutes after Car K does Let''s calculate the distance that Car ...”
November 2, 2018
Brent@GMATPrepNow posted a reply to At a family summer party, each of the x members of the in the Problem Solving forum
“Let''s use the INPUT-OUTPUT approach. It might be useful to choose a number that works well with the fractions given in the question (1/3 and 1/7). So, let''s say there are 21 family members at the party. In other words, we''re saying that x = 21 1/3 chose to have a hamburger, and of ...”
November 1, 2018
Brent@GMATPrepNow posted a reply to When a positive integer n is divided by 19, what is the rema in the Data Sufficiency forum
“Target question: When n is divided by 19, what is the remainder? Statement 1: n-17 is a multiple of 19 ----ASIDE------------------------------------------- If N is a multiple of d, then we can write N = dk (for some integer k) For example, if N is a multiple of 5, then we can write N = 5k ...”
November 1, 2018
Brent@GMATPrepNow posted a reply to In the diagram above, points A, B, C, D, and E represent the in the Problem Solving forum
“points A, B, C, D, and E represent the five teams in a certain league in which each team must play each of the other teams exactly once. Let''s first determine the total number of games that will be played. There are 5 teams, so each team will play 4 games (since a team can''t play itself) So, ...”
November 1, 2018
Brent@GMATPrepNow posted a reply to In four years, Andy will be twice as old as Betsy. How old in the Data Sufficiency forum
“ Given: In four years, Andy will be twice as old as Betsy. Let A = Andy''s PRESENT age Let B = Betsy''s PRESENT age So, A+4 = Andy''s age IN 4 YEARS And so, B+4 = Betsy''s age IN 4 YEARS If Andy will be twice as old as Betsy IN 4 YEARS, we can write: A+4 = 2(B+4) Expand: A + 4 = 2B + 8 ...”
October 31, 2018
Brent@GMATPrepNow posted a reply to If m and n are integers, is m+m^2-n an even number? in the Data Sufficiency forum
“ Given: m and n are integers Target question: Is m + m² - n an even number? This is a good candidate for rephrasing the target question Aside: Here’s a video with tips on rephrasing the target question: We can take the expression, m + m² - n and rewrite it as m(1 + m) - n Now notice ...”
October 31, 2018
Brent@GMATPrepNow posted a reply to In 1995 a certain store had 1,800 tools in stock that had in the Problem Solving forum
“1,000 of these tools were sold in 1995 for $40 each So, the REVENUE = (1000)($40) = $40,000 The 1000 tools were purchased for$30 each. So, the EXPENSE = (1000)($30) =$30,000 PROFIT for 1995 = $40,000 -$30,000 = $10,000 ----------------------------------------------- The remaining 800 ...” October 31, 2018 Brent@GMATPrepNow posted a reply to Tom, Bill, Robert, Roger, and Terry are standing in a row in the Problem Solving forum “One approach is to ignore the rule and determine the total number of ways to arrange all 5 people, and then subtract the number of arrangements that BREAK the rule. I''m sure someone will post that kind of solution shortly. Here''s another approach: Take the task of arranging the 5 men and ...” October 30, 2018 Brent@GMATPrepNow posted a new topic called Challenge #2: If x and y are different positive integers, wh in the Problem Solving forum “If x and y are different positive integers, which of the following COULD be true: i) When x is divided by y, the remainder is 2x ii) When x is divided by 2y, the remainder is y iii) When (2x + y) is divided by (x + y), the remainder is y A) i only B) ii only C) iii only D) i & ii ...” October 30, 2018 Brent@GMATPrepNow posted a reply to Challenge: If x and y are different positive integers, which in the Problem Solving forum “i) When x is divided by y, the remainder is x This occurs any time x < y For example, if x = 5 and y = 7, then statement i becomes: When 5 is divided by 7, the remainder is 5 So true! Scan the answer choices....eliminate D ----------------------------------------------------- ii) When 2x ...” October 30, 2018 Brent@GMATPrepNow posted a reply to Carmelo and LeBron participate in a seven-person footrace on in the Problem Solving forum “Here are three similar questions to practice with: - http://www.beatthegmat.com/counting-six-mobsters-t47167.html - http://www.beatthegmat.com/permutation-and-combination-t273916.html - http://www.beatthegmat.com/permutations-with-waiting-line-t274020.html Cheers, Brent” October 30, 2018 Brent@GMATPrepNow posted a reply to A certain basket contains 10 apples, 7 of which are red and in the Problem Solving forum “Jay has demonstrated a solution that involves counting techniques. Here''s one that involves probability rules. Let''s find the probability of selecting a red apple 1st, a red apple 2nd, and a green apple 3rd (aka RRG) P(red apple 1st AND red apple 2nd AND green apple 3rd) = P(red apple 1st) x ...” October 30, 2018 Brent@GMATPrepNow posted a reply to A salesperson for an automobile dealer earns an annual in the Problem Solving forum “Total earnings = (base salary) + (commission) base salary =$25,000 commission = 10% of total sales OVER $100,000 = 10% of (x -$100,000) = 0.1(x - $100,000) So, total earnings =$25,000 + 0.1(x - $100,000) Answer: E Cheers, Brent” October 30, 2018 Brent@GMATPrepNow posted a reply to There are 16 teams in a soccer league, and team plays each in the Problem Solving forum “Another approach: The question is really asking, "In how many different ways can we create 2-team pairings from 16 teams?" Since the order of the selections does not matter (i.e., selecting teams A and B to play, is the same as selecting teams B and A to play), we can use combinations. ...” October 30, 2018 Brent@GMATPrepNow posted a reply to There are 16 teams in a soccer league, and team plays each in the Problem Solving forum “There are 16 teams. If we ask each team, "How many teams did you play?" we''ll find that each team played 15 teams, which gives us a total of 240 games (since 16 x 15 = 240). From here we need to recognize that each game has been COUNTED TWICE. For example, if Team A and Team B play ...” October 30, 2018 Brent@GMATPrepNow posted a reply to For integers a, b, c, a/(b - c)=1 what is the value of (b-c) in the Data Sufficiency forum “ Given: a/(b - c) = 1 Target question: What is the value of (b-c)/b ? This is a good candidate for rephrasing the target question. Aside: Here’s a video with tips on rephrasing the target question: If a/(b - c) = 1, then we know that a = b - c The target question asks "What is the ...” October 29, 2018 Brent@GMATPrepNow posted a reply to If a and b are integers such that a > b > 1, which of in the Problem Solving forum “Let''s make an important observation. Some positive multiples of 3 are: 3, 6, 9, 12, . . . . Some positive multiples of 5 are: 5, 10, 15, 20, . . . . Some positive multiples of 12 are: 12, 24, 36, 48, . . . . General observation: the positive multiples of k are all greater than or equal to k ...” October 29, 2018 Brent@GMATPrepNow posted a new topic called Challenge: If x and y are different positive integers, which in the Problem Solving forum “If x and y are different positive integers, which of the following COULD be true: i) When x is divided by y, the remainder is x ii) When 2x is divided by y, the remainder is x iii) When x+y is divided by x , the remainder is x-y A) i only B) i & ii only C) i & iii only D) ii & ...” October 29, 2018 Brent@GMATPrepNow posted a reply to What is the value of x? in the Data Sufficiency forum “Target question: What is the value of x? Statement 1: (x + 2)(x + 3) = 0 This means that EITHER x = -2 OR x = -3 Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT Statement 2: x² + 5x + 6 = 0 Factor the left side of the equation to get: (x + 2)(x ...” October 29, 2018 Brent@GMATPrepNow posted a reply to A length of rope is cut into three different lengths. What in the Data Sufficiency forum “Target question: What is the length of the shortest rope? Let''s assign some variables. Let x = length of shortest rope Let y = length of middle rope Let z = length of longest rope Statement 1: The combined length of the longest two pieces is 6 feet. In other words, y + z = 6 Since we ...” October 28, 2018 Brent@GMATPrepNow posted a reply to Challenge question: At noon, Joe and a hummingbird leave in the Problem Solving forum “The main idea here is that all 3 travelers travel for the SAME amount of time. So, let''s first determine the time it takes for Joe and Sue to meet. This is a shrinking gap question. To determine the rate at which the gap shrinks, we''ll ADD the travel speeds of Joe and Sue That is, ...” October 28, 2018 Brent@GMATPrepNow posted a reply to If x and y are positive, what is the value of y ? in the Data Sufficiency forum “Target question: What is the value of y? Given: x and y are positive Statement 1: xy is the square of an integer. There are several values of x and y that satisfy this condition. Here are two: Case a: x = 1 and y = 1. Here xy = (1)(1) = 1, which is the square of an integer. In this ...” October 28, 2018 Brent@GMATPrepNow posted a new topic called Challenge question: At noon, Joe and a hummingbird leave in the Problem Solving forum “At noon, Joe and a hummingbird leave point A and travel towards point B, which is 12 miles away. At the same time Sue leaves point B and travels toward point A. Joe, Sue and the hummingbird travel at constant speeds of 3 miles per hour, 4 miles per hour, and 84 miles per hour respectively. When the ...” October 27, 2018 Brent@GMATPrepNow posted a reply to There are n students in a class. Of them, k boys and k girls in the Data Sufficiency forum “Target question: What is the probability that Harvey will be paired with Jessica? Given: There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. ...” October 27, 2018 Brent@GMATPrepNow posted a reply to When the positive integer n is divided by 25, the remainder in the Data Sufficiency forum “Target question: What is the value of n? Given: When the positive integer n is divided by 25, the remainder is 13. -------ASIDE------------- When it comes to remainders, we have a nice rule that says: If N divided by D leaves remainder R, then the possible values of N are R, R+D, R+2D, ...” October 27, 2018 Brent@GMATPrepNow posted a reply to A circus clown is entertaining kids by making balloon in the Problem Solving forum “As with many probability questions, we can solve this by using counting techniques or rules of probability. Let''s use rules of probability P(balloon animal is an elephant) = 1/4 P(balloon animal is purple) = 1/5 P(clown makes a purple elephant balloon animal) = P(balloon animal is ...” October 27, 2018 Brent@GMATPrepNow posted a reply to In a right triangle, the longer leg is two more than three in the Problem Solving forum “In a right triangle, the longest side is called the hypotenuse, and the two sides that meet to create a 90-degree angle are called the legs. So, one leg will be the triangle''s base, and the other leg will be the triangle''s height. Let x = length of the triangle''s base (which, for this ...” October 27, 2018 Brent@GMATPrepNow posted a reply to If a and b are two positive numbers, what is the product of in the Data Sufficiency forum “Target question: What is the value of ab? Statement 1: The LCM of a and b is 16 Let''s TEST some values. There are several values of a and b that satisfy statement 1. Here are two: Case a: a = 1 and b = 16 (the LCM of 1 and 16 is 16). In this case, the answer to the target question is ab = ...” October 26, 2018 Brent@GMATPrepNow posted a reply to In the mid-1960's a newly installed radar warning system in the Sentence Correction forum “The idiom here is "Mistake x FOR y" So, we can eliminate A, C and E We''re left with B and D D conveys an ambiguous message, because it suggests that the moon was rising for an attack. ELIMINATE D Answer: B Cheers, Brent” October 26, 2018 Brent@GMATPrepNow posted a reply to What is the largest prime factor of the expression 3^8 − 2 in the Problem Solving forum “There''s a difference of squares "hiding" in the expression 3^8 − 2^12 That is 3^8 − 2^12 = (3^4)² − (2^6)² We know that: x² - y² = (x + y)(x - y) So, we get: (3^4)² − (2^6)² = (3^4 + 2^6)(3^4 - 2^6) = (81 + 64)(81 - 64) = (145)(17) = (5)(29)(17) The greatest ...” October 26, 2018 Brent@GMATPrepNow posted a reply to When Q is divided by W, the quotient is R and the remainder in the Problem Solving forum “-----ASIDE----------------------- There''s a nice rule that says, "If N divided by D equals Q with remainder R, then N = DQ + R" For example, since 17 divided by 5 equals 3 with remainder 2, then we can write 17 = (5)(3) + 2 Likewise, since 53 divided by 10 equals 5 with remainder 3, ...” October 26, 2018 Brent@GMATPrepNow posted a reply to Tricky: If AB || DE, and AB = 10, what is the length of DE? in the Data Sufficiency forum “Let''s first add the given information (and their implications) to the diagram If AB || DE, we know that ∠BAC = ∠CED and ∠ABC = ∠DCE Also, since vertically opposite angles are equal, we know that ∠ACB = ∠DCE https://i.imgur.com/fgDp7Yh.png Now that we''ve identified 3 pairs of ...” October 26, 2018 Brent@GMATPrepNow posted a new topic called Tricky: If AB || DE, and AB = 10, what is the length of DE? in the Data Sufficiency forum “https://i.imgur.com/jyTAK6n.png If AB || DE, and AB = 10, what is the length of DE? (1) BC = 6 and CE = 4 (2) DC = 3 and CB = 6 Answer: B Difficulty level: 650 – 700 Source: www.gmatprepnow.com” October 25, 2018 Brent@GMATPrepNow posted a reply to If |x-6|=2x, then x=? in the Problem Solving forum “There are 3 steps to solving equations involving ABSOLUTE VALUE: 1. Apply the rule that says: If |x| = k, then x = k or x = -k 2. Solve the resulting equations 3. Plug solutions into original equation to check for extraneous roots Step 1: x - 6 = 2x or x - 6 = -2x case a: x - 6 = 2x Step ...” October 25, 2018 Brent@GMATPrepNow posted a reply to CHALLENGE: 10 teams (A, B, C, D, E, F, G, H, I and J) partic in the Problem Solving forum “First determine the TOTAL number of games played. We can select 2 teams from 10 teams in 10C2 ways (= 45 ways) So, there will be 45 games in TOTAL IMPORTANT: Each team plays 9 games For each game, 2 points are awarded. So, the TOTAL number of POINTS awarded = (2)(45) = 90 Teams A, B, C, ...” October 24, 2018 Brent@GMATPrepNow posted a reply to Noelle walks from point A to point B at an average speed of in the Problem Solving forum “For these kinds of questions, I typically follow the approach that Fabio used (assign a nice value to the distance). But we can also solve the question algebraically: Let d = the distance between Points A and B. Let x = the Noelle''s speed from Point B to Point A. We want the average ...” October 24, 2018 Brent@GMATPrepNow posted a reply to What is the median number of employees assigned per project in the Data Sufficiency forum “Target question: What is the median number of employees assigned per project? Statement 1: 25 percent of the projects at Company Z have 4 or more employees assigned to each project. Let''s pretend that there are 4 projects altogether. There are several sets of values that meet this condition. ...” October 24, 2018 Brent@GMATPrepNow posted a reply to In a certain company, the ratio of the number of manager to in the Problem Solving forum “One option is to use TWO VARIABLES Let M = CURRENT # of managers Let W = CURRENT # of production-line workers The ratio of the number of managers to the number of production-line workers is 5 to 72. So, we can write: M/W = 5/72 Cross multiply to get: 5W = 72M If 8 additional ...” October 23, 2018 Brent@GMATPrepNow posted a reply to When 100 is divided by positive integer x, the remainder is in the Problem Solving forum “A fast approach is to find a value of x that meets the given condition: When 100 is divided by positive integer x, the remainder is 2 Well, x = 98 satisfies that condition, since 100 divided by 98 = 1 with remainder 2 What is the remainder when 198 is divided by x? Well, 198 divided by 98 ...” October 23, 2018 Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum “Range and Standard Deviation Video: https://www.youtube.com/watch?v=FbAlIjw2fwY Cheers, Brent” October 23, 2018 Brent@GMATPrepNow posted a reply to Which of the following values, when inserted into the set of in the Problem Solving forum “Let''s test each answer choice.... A. 2 The new set becomes {2, 5, 10, 12, 13, 17, 22, 22} Since we have an EVEN number of values in the set, the median equals the average of the two middlemost numbers. So, median = (12 + 13)/2 = 25/2 = 12.5 No good - we want the median to be 15 B. ...” October 23, 2018 Brent@GMATPrepNow posted a reply to What are the coordinates of point B in the figure above ? in the Data Sufficiency forum “IMPORTANT: For geometry Data Sufficiency questions, we are typically checking to see whether the statements "lock" a particular angle, length, or shape into having just one possible measurement. This concept is discussed in much greater detail in the video below. Target question: What ...” October 23, 2018 Brent@GMATPrepNow posted a reply to The range of set A is 24 and the range of set B is 20. What in the Problem Solving forum “If the range of set A is 24, and we add more values (from set B) to set A, then the range of the resulting set must be greater than or equal to 24 (that is, the range of a set cannot get smaller upon adding MORE numbers to that set). For this reason, we can ELIMINATE answer choice A. From ...” October 23, 2018 Brent@GMATPrepNow posted a reply to If x and y are positive integers, what is the remainder when in the Data Sufficiency forum “ Given: x and y are positive integers Target question: What is the remainder when x^y is divided by 10? This is a good candidate for rephrasing the target question. Notice that 43 divided by 10 leaves remainder 3, and 127 divided by 10 leaves remainder 7, and 618 divided by 10 leaves ...” October 23, 2018 Brent@GMATPrepNow posted a new topic called CHALLENGE: 10 teams (A, B, C, D, E, F, G, H, I and J) partic in the Problem Solving forum “10 teams (A, B, C, D, E, F, G, H, I and J) participate in a soccer tournament in which each team plays every other team once. For each game played, points are awarded to the teams as follows: 0 points for losing the game 1 point each for tying the game 2 points for winning the game After ...” October 22, 2018 Brent@GMATPrepNow posted a reply to Clarissa will create her summer reading list by randomly in the Problem Solving forum “Take the task of creating the reading list and break it into stages. Stage 1: Select a book to read 1st There are 10 books to choose from. So, we can complete stage 1 in 10 ways Stage 2: Select a book to read 2nd There are 9 books remaining to choose from (since we already chose a book ...” October 22, 2018 Brent@GMATPrepNow posted a reply to A jar contains only green pencils and red pencils. If the in the Data Sufficiency forum “Target question: What percentage of the pencils are green? Given: The jar contains only green pencils and red pencils. Statement 1: The jar contains 75 red pencils. If 75 of the 225 pencils are red, then the remaining 150 pencils are GREEN. 150/225 = 2/3 = 66 2/3%, so the answer to ...” October 22, 2018 Brent@GMATPrepNow posted a reply to Challenge Question: In the x-y coordinate plane, does line k in the Data Sufficiency forum “Target question: Does line k have a positive x-intercept? Statement 1: (slope of line k)(y-intercept of line k) > 0 There are two possible cases that that satisfy statement 1: - the slope and y-intercept are both positive - the slope and y-intercept are both negative Let''s examine ...” October 21, 2018 Brent@GMATPrepNow posted a reply to What is the area of the triangle formed by the intersection in the Problem Solving forum “Here''s a similar question to practice with: https://www.beatthegmat.com/area-of-triangle-formed-by-intersections-of-3-lines-t276079.html Cheers, Brent” October 21, 2018 Brent@GMATPrepNow posted a new topic called Challenge Question: In the x-y coordinate plane, does line k in the Data Sufficiency forum “In the x-y coordinate plane, does line k have a positive x-intercept? (1) (slope of line k)(y-intercept of line k) > 0 (2) (slope of line k) - (y-intercept of line k) < 0 Answer: A Difficulty level: 650 – 700 Source: www.gmatprepnow.com” October 19, 2018 Brent@GMATPrepNow posted a reply to When positive integer N is divided by positive integer J, in the Problem Solving forum “ASIDE: 7/2 = 3 1/2 = 3 + 0.5 = 3.5 Notice that 1 is the remainder when we divide 7 by 2. 23/5 = 4 3/5 = 4 + 0.6 = 4.6 Notice that 3 is the remainder when we divide 23 by 5. 31/4 = 7 3/4 = 7 + 0.75 = 7.75 Notice that 3 is the remainder when we divide 31 by 4. GIVEN: N/J = 134.08 This means ...” October 19, 2018 Brent@GMATPrepNow posted a reply to If there are more than two numbers in a certain list, is in the Data Sufficiency forum “[quote="Jay@ManhattanReview"] Hey Jay, I thought I should point out that case 2 doesn''t satisfy the statement. If we choose 1 and 2 from the set, then the product isn''t 0. That said, {0, 0, 0, 0, 1} meets the given condition, as does {0, 0, 0, 0, 0, 0, 0, 3} etc Cheers, ...” October 19, 2018 Brent@GMATPrepNow posted a reply to If -1<x<0, Which of the following is listed in ascendi in the Problem Solving forum “Let''s test a value of x. If -1 < x < 0, then x COULD equal -1/2 So, x^(-1) = (-1/2)^(-1) = 1/(-1/2) = -2 And, x^(-2) = (-1/2)^(-2) = 1/(-1/2)^2 = 1/(1/4) = 4 And, x^2 = (-1/2)^2 = 1/4 Listed in ascending order, we get: -2, 1/4, 4 In other words, x^(-1), x^2, x^(-2) Answer: A ...” October 19, 2018 Brent@GMATPrepNow posted a reply to The latest model of space shuttle can achieve a maximum in the Problem Solving forum “GIVEN: The shuttle can travel 25 miles in 1 second So, the shuttle can travel 1500 miles in 60 seconds In other words, the shuttle can travel 1500 miles in 1 MINUTE So, the shuttle can travel 90,000 miles in 60 MINUTES In other words, the shuttle can travel 90,000 miles in 1 HOUR In other ...” October 18, 2018 Brent@GMATPrepNow posted a reply to A jar contains 6 red marbles and 9 blue marbles. If Evelyn in the Problem Solving forum “P(both are same color) = P(1st marble is red AND 2nd marble is red OR 1st marble is blue AND 2nd marble is blue) = x P(2nd marble is red)] + x P(2nd marble is blue)] = x 5/14] + x 8/14] = x 5/14] + x 8/14] = 10/70 + 24/70 = 34/70 = 17/35 Answer: D Cheers, Brent” October 18, 2018 Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum “Time management strategy for test day Video: https://www.youtube.com/watch?v=bWrUiBT83PQ Cheers, Brent” October 18, 2018 Brent@GMATPrepNow posted a reply to In the x-y coordinate plane, line k passes through in the Problem Solving forum “Notice that, if the line passes through the origin, then the line has slope -4/5 (aka a slope of -0.8), but the line will not have a negative x-intercept Notice that, if the line passes through the (0,4), then the line will have slope 0, BUT the line will not have a negative x-intercept. See ...” October 18, 2018 Brent@GMATPrepNow posted a reply to f[f{f(x)}]=??? in the GMAT Math forum “Useful property: 1/(a/b) = b/a We want: ff(5)}] = f1/6}] f{1/6} = 1/(1 + 1/6) = 1/(7/6) = 6/7 So, ff{1/6}] = f6/7] Finally, f[6/7] = 1/(1 + 6/7) = 1/(13/7) = 7/13 Answer: B (since 21/39 reduces to the equivalent fraction 7/13) Cheers, Brent” October 18, 2018 Brent@GMATPrepNow posted a reply to In the month of August, Pentheus Corporation made$200,000 in the Problem Solving forum
“In the month of August, Pentheus Corporation made $200,000 in profit. Pentheus made 6% of that profit on the second Wednesday of August. 1% of$200,000 = $2,000, so 6% of$200,000 = (6)($2,000) =$12,000 So, the profit on that day = $12,000 If the profits that day were approximately 14.5% of ...” October 18, 2018 Brent@GMATPrepNow posted a reply to Brian purchased a bouquet of 40 flowers for his mother for in the Problem Solving forum “We can solve this question using either 1 variable or 2 variables. Here''s an approach that involves 1 variable: Let t = # of tulips in bouquet So. 40 - t = # of roses in bouquet So, ($1.00)(t) = the total COST of all t tulips And ($1.50)(40 - t) = the total COST of all 40-t roses ...” October 18, 2018 Brent@GMATPrepNow posted a reply to In a town of 8,000 residents, 65 percent of all residents in the Problem Solving forum “Another approach is to use the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it (aka overlapping sets questions). Here, we have a population of residents, and the two characteristics are: ...” October 17, 2018 Brent@GMATPrepNow posted a reply to What is the remainder if 7^10 is divided by 100? in the Problem Solving forum “Sweeeeeeeeeeeeet solution, Scott!! Cheers, Brent” October 17, 2018 Brent@GMATPrepNow posted a reply to If x, y, and z are all nonzero numbers, and x = y + z, which in the Problem Solving forum “NOTE: this is one of those questions that require us to check/test each answer choice. In these situations, always check the answer choices from E to A, because the correct answer is typically closer to the bottom than to the top. For more on this strategy, see my article: ...” October 16, 2018 Brent@GMATPrepNow posted a reply to Set X consists of different positive numbers arranged in in the Data Sufficiency forum “Target question: What is the arithmetic mean of set X? Given: Set X consists of different positive numbers arranged in ascending order: K, L, M, 5, 7. K, L and M are consecutive integers This means that EITHER K, L, M = 1, 2, 3 respectively, OR K, L, M = 2, 3, 4 respectively Head straight ...” October 16, 2018 Brent@GMATPrepNow posted a reply to A Martian bat flies at 60 yards per second from its nest to in the Problem Solving forum “Rich''s approach is definitely the best (i.e., fastest) way to solve this question. However, if the answer choices weren''t so sweet, here''s an algebraic solution Average speed = (total distance traveled)/(total travel time) Let''s assign nice values to the distances. These values should ...” October 16, 2018 Brent@GMATPrepNow posted a reply to Charlie takes 2.5 hours to fly from Los Angeles to Mexico in the Problem Solving forum “Average speed = (total distance traveled)/(total travel time) So, Average speed = 1200/2.5 = 2400/5 = 4800/10 = 480 mph Answer: D Cheers, Brent” October 16, 2018 Brent@GMATPrepNow posted a reply to A certain NYC taxi driver has decided to start charging a in the Problem Solving forum “Here''s an algebraic approach: A certain taxi driver charges a rate of r CENTS per person per mile r CENTS = r/100 DOLLARS Since there are 3 people, the rate is (3)(r/100) DOLLARS per mile In other words, the rate is 3r/100 dollars per mile. With a 50% discount, the new rate = ...” October 16, 2018 Brent@GMATPrepNow posted a new topic called In the x-y coordinate plane, line k passes through in the Problem Solving forum “In the x-y coordinate plane, line k passes through the point (5, -4) and has a negative x-intercept. Which of the following COULD be the equation of line k? i) y = -0.4x - 2 ii) y = 2 - 1.2x iii) y = -0.7x - 1.5 A) i only B) ii only C) iii only D) i & ii only E) i & iii only ...” October 16, 2018 Brent@GMATPrepNow posted a reply to Lindsay can paint 1/x of a certain room in one hour. If in the Problem Solving forum “This appears to be a slightly different version of this official question: https://www.beatthegmat.com/work-rate-problem-5-t292679.html HOWEVER, unless I''m missing something, the correct answer is missing. Cheers, Brent” October 15, 2018 Brent@GMATPrepNow posted a reply to How many factors does the number X have? in the Data Sufficiency forum “Target question: How many factors does the number X have? Statement 1: X is divisible by 47 Let''s TEST some values. There are several values of X that satisfy statement 1. Here are two: Case a: X = 47. The factors of 47 are {1, 47}. So, the answer to the target question is X has 2 ...” October 15, 2018 Brent@GMATPrepNow posted a reply to A rectangular solid S, has dimensions 4 by 9 by k. What is in the Data Sufficiency forum “Target question: What is the value of k? Given: A rectangular solid S, has dimensions 4 by 9 by k Statement 1: 4 < k < 9 Since k can have ANY value between 4 and 9, statement 1 is NOT SUFFICIENT Statement 2: A cube of side 6 has the same volume as rectangular solid S. So ...” October 15, 2018 Brent@GMATPrepNow posted a reply to In the rectangular coordinate system above, if the in the Data Sufficiency forum “I think that, if this were an official GMAT question, the correct answer would be E (not B), because we aren''t specifically told that the dotted lines are parallel to the x-axis and the y-axis. If those dotted lines aren''t parallel to those axes, the we can''t determine the value of y. ...” October 15, 2018 Brent@GMATPrepNow posted a reply to In the figure above, triangle ABC is equilateral, and point in the Problem Solving forum “It may help to add some lines to the diagram. First add lines from the center to the 3 vertices. https://s8.postimg.cc/e412m8uq9/clk1.jpg Aside, we know that each angle is 120º since all three (equivalent) angles must add to 360.º Then draw a circle so that the triangles vertices are on ...” October 15, 2018 Brent@GMATPrepNow posted a reply to The mass of 1 cubic meter of a substance is 800 kg under in the Problem Solving forum “GIVEN: 1 cubic METER of the substance weighs 800 KILOGRAMS 1 kg =1,000 grams, so we can write: 1 cubic METER of the substance weighs 800,000 GRAMS 1 cubic meter = 1,000,000, so we can write: 1,000,000 cubic CENTIMETERS of the substance weighs 800,000 GRAMS What is the volume in cubic ...” October 14, 2018 Brent@GMATPrepNow posted a reply to At a family summer party, each of the x members of the in the Problem Solving forum “These kinds of questions (Variables in the Answer Choices - VIACs) can be answered algebraically or using the INPUT-OUTPUT approach. The Ash Mo solved the question algebraically, so let''s use the INPUT-OUTPUT approach. It might be useful to choose a number that works well with the fractions ...” October 13, 2018 Brent@GMATPrepNow posted a reply to When A and B are positive integers, is AB a multiple of 4? in the Data Sufficiency forum “Target question: Is AB a multiple of 4? Useful property: If N is divisible by d, we can say that N = dk for some integer k For example, if N is divisible by 5, we can say that N = 5k for some integer k Statement 1: The greatest common divisor of A and B is 6 This means that A is divisible ...” October 13, 2018 Brent@GMATPrepNow posted a reply to How much time did it take a certain car to travel 400 in the Data Sufficiency forum “Target question: How long did it take to travel 400km To find the travel time, we need to know the average speed traveled. Let x = the average speed traveled. REPHRASED target question: What is the value of x? Statement 1: The car traveled the first 200 km in 2.5 hrs No info about the ...” October 13, 2018 Brent@GMATPrepNow posted a reply to Challenge question: What is the sum of all in the Problem Solving forum “Approach #1 If we recognize that x^(2/3) = u-substitution. Let u = x^(1/3) Now take original equation and replace x^(1/3) with u to get: u² - u - 2 = 4 Subtract 4 from both sides to get: to get: u² - u - 6 = 0 Factor: (u - 3)(u + 2) = 0 So, the two solutions here are u = 3 and u = -2 ...” October 13, 2018 Brent@GMATPrepNow posted a reply to A certain club has 10 members, including Harry. One of the 1 in the Problem Solving forum “As with many probability questions, we can solve this using counting techniques or probability rules. So, before you embark on one approach, try to determine which one is faster. Here''s the probability approach: P(Harry selected Secretary or Treasurer) = 1 - P(Harry selected president OR ...” October 13, 2018 Brent@GMATPrepNow posted a reply to The average age of a group of n people is 15 yrs. One more in the Problem Solving forum “The average age of a group of n people is 15 yrs. So, (sum of all n ages)/n = 15 Multiply both sides by n to get: (sum of all n ages) = 15n One more person aged 39 joins the group and the new average is 17 yrs. IMPORTANT: Once this 39-year-old is added to the group, the (NEW sum of ages) = ...” October 12, 2018 Brent@GMATPrepNow posted a new topic called Challenge question: What is the sum of all in the Problem Solving forum “What is the sum of all solutions to the equation x^(2/3) - x^(1/3) - 2 = 4? A) -35 B) -19 C) 7 D) 19 E) 35 Answer: D Source: www.gmatprepnow.com Difficulty level: 600 - 650” October 12, 2018 Brent@GMATPrepNow posted a reply to Challenge question: j and k are positive integers in the Data Sufficiency forum “ Given: n = 10^j + k Target question: Is n divisible by 15? Key concepts: - If n is divisible by 15, then n must be divisible by 3 AND by 5 - If n is divisible by 3, then the sum of n''s digits must be divisible by 3 (for example, we know that 747 is divisible by 3, because 7+4+7 = 18, ...” October 12, 2018 Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum “Here''s our video on "if" versus "whether" https://www.youtube.com/watch?v=F2ZHtB088us Cheers, Brent” October 11, 2018 Brent@GMATPrepNow posted a new topic called Challenge question: j and k are positive integers in the Data Sufficiency forum “j and k are positive integers, and n = 10^j + k. Is n divisible by 15? (1) j and k are each divisible by 3 (2) j and k are each divisible by 5 Answer: A Difficulty level: 700+ Source: www.gmatprepnow.com” October 11, 2018 Brent@GMATPrepNow posted a reply to Julie opened a lemonade stand and sold lemonade in two in the Data Sufficiency forum “This question illustrates a common trap on the GMAT. For statement 2, we''re able to write the equation 52x + 58y = 492 , and in high school we learned that, if we''re given 1 equation with 2 variables, we cannot find the value of either variable. However, if we restrict the variables to ...” October 11, 2018 Brent@GMATPrepNow posted a reply to There are 5 cars to be displayed in 5 parking spaces with in the Problem Solving forum “Let R, R, R, B, Y represent the cars (by their colors) Notice that the three R''s are identical. So, the question becomes In how many different ways can we arrange the letters R, R, R, B and Y? ----------------ASIDE------------------------------ When we want to arrange a group of items in ...” October 10, 2018 Brent@GMATPrepNow posted a reply to Is x/11 an integer? in the Data Sufficiency forum “Target question: Is x/11 an integer? Statement 1: 5x/11 is an integer Let''s TEST some values There are several values of x that satisfy statement 1. Here are two: Case a: x = 11. Notice that 5x/11 = 5(11)/11 = 5, which is an integer. In this case, x/11 = 11/11 = 1. So, the answer to the ...” October 10, 2018 Brent@GMATPrepNow posted a reply to Dick and Jane each saved$3000 in 1989. In 1990 Dick save 8 in the Problem Solving forum
“Here''s the original wording: In 1990, Dick saved 8 percent more than in 1989 So, Dick''s savings in 1990 = 1.08($3000) =$3240 In 1990, Dick and Jane saved a total of $5,000. So, Jane''s savings =$5,000 - $3240 =$1760 Approximately what percent less did Jane save in 1990 than in ...”
October 10, 2018
Brent@GMATPrepNow posted a reply to Pam and Sue drove in the same car to a business meeting that in the Problem Solving forum
“Travel time = distance/speed Pam''s travel time = 120 miles/60 mph =2 hours Sue''s travel time = 120 miles/50 mph =2.4 hours Time difference = 2.4 hours - 2 hours = 0.4 hours To convert 0.4 hours to minutes, recognize that 1 hour = 60 minutes So, 0.4 hours = (0.4)(60) minutes = 24 minutes ...”
October 10, 2018
Brent@GMATPrepNow posted a reply to A group of medical interns at Bohemus Medical School want to in the Problem Solving forum
“Take the task of arranging dates and break it into stages. Let A, B, C, D and E represent the 5 girls Stage 1: Select a boy to date girl A We can choose any of the 5 boys, so we can complete stage 1 in 5 ways Stage 2: Select a boy to date girl B Since we already selected a boy in ...”
October 9, 2018
Brent@GMATPrepNow posted a reply to A school library contains 200 hardcover and 300 paperback in the Problem Solving forum
“Another approach is to use the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it (aka overlapping sets questions). Here, we have a population of books, and the two characteristics are: - ...”
October 9, 2018
Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“Here''s our video on the Double Matrix Method for overlapping sets: https://www.youtube.com/watch?v=jK-tiBrrf04 Cheers, Brent”
October 9, 2018
Brent@GMATPrepNow posted a reply to If x, y, and z are positive numbers, Is z between x and y? in the Data Sufficiency forum
“Target question: Is z between x and y? Statement 1: x < 2z < y There are several sets of values of x, y and z that satisfy this condition. Here are two: Case a: x = 3, y = 10, and z = 2, in which case z is NOT between x and y Case b: x = 1, y = 10, and z = 3, in which case z IS ...”
October 9, 2018
Brent@GMATPrepNow posted a reply to If the product of X and Y is a positive number, is the sum in the Data Sufficiency forum
“IMPORTANT CONCEPTS: An ODD power preserves the sign of the base. For example, (-5)^3 = -125 and 2^5 = 32 An EVEN power always yields a positive number (as long as the base ≠ 0 For example, (-5)^4 = 625 and 2^6 = 64 Target question: Is the sum of x and y negative? Given: the ...”
October 9, 2018
Brent@GMATPrepNow posted a reply to DS: Difficulty level: 700, Source: Economist in the GMAT Math forum
“The key word here is must So, if we can find a case in which an answer choice is NOT true, then we can eliminate that answer choice. A. x is odd and y is even. x = 3 and y = 11 satisfies the condition that x/y is not an integer Since y is NOT even, we can ELIMINATE A B. x is odd and y is ...”
October 9, 2018
Brent@GMATPrepNow posted a reply to James invested $5000 in scheme A for 1 year at a simple in the Problem Solving forum “Scheme A Interest = 5% of$5,000 = $250 Scheme B 10% interest compounded semi-annually means that the interest is compounded 2 times (in 1 year) at a rate of 5% each time One option is to apply the compound interest formula, but since we''re only compounding the interest twice, it may be ...” October 9, 2018 Brent@GMATPrepNow posted a reply to A retailer buys cases of 24 shirts for$30/case and then in the Problem Solving forum
“The key information here is that the retailer sold all the shirts it purchased This is a huge hint! For example, we know that the retailer did NOT buy only 1 case of 24 shirts, because 24 shirts will not divide into packs of 5 shirts. Likewise, we know that the retailer did NOT buy 2 cases of ...”
October 8, 2018
Brent@GMATPrepNow posted a reply to If x^2-3x=10, what is the value of x? in the Data Sufficiency forum
“ Given: x² - 3x = 10 Subtract 10 from both sides to get: x² - 3x - 10 = 0 Factor: (x - 5)(x + 2) = 0 So, EITHER x = 5 OR x = -2 Target question: What is the value of x? Statement 1: x² - 4 = 0 Factor: (x + 2)(x - 2) = 0 So, EITHER x = -2 OR x = 2 When we combine this with the fact ...”
October 8, 2018
Brent@GMATPrepNow posted a reply to What is the greatest prime factor of 1+2+3+….+36? in the Problem Solving forum
“Useful formula: 1 + 2 + 3 + 4 + . . . . + n = (n)(n + 1)/2 So, 1 + 2 + 3 + …. + 36 = (36)(36 + 1)/2 = (36)(37)/2 = (18)(37) = (2)(3)(3)(17) So, the greatest prime factor is 37 Answer: E Cheers, Brent”
October 8, 2018
Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“In this short (3:25) video, we''ll examine the age-old question When do I use IF and when do we use WHETHER? Video link: https://www.youtube.com/watch?v=F2ZHtB088us Cheers, Brent”
October 7, 2018
Brent@GMATPrepNow posted a reply to All assets in Karina's investment portfolio are divided in the Problem Solving forum
“Let''s say Karina''s entire portfolio is worth $100 altogether. So, we want to divide this$100 into four integer amounts: w, x, y, z, where w < x < y < z, and we want to minimize the value of z In order to MINIMIZE the value of the z, we must MAXIMIZE the values of w, x, and y. Now ...”
October 7, 2018
Brent@GMATPrepNow posted a reply to Beth and Jim each received a salary increase. If Jim's in the Data Sufficiency forum
“Target question: Did Beth receive a greater dollar increase in salary than Jim? Given: Jim''s salary was increased by the same percent as Beth''s salary Statement 1: Before the increases, Jim''s salary was greater than $25,000. Since we have no information about Beth, there''s no way to ...” October 7, 2018 Brent@GMATPrepNow posted a reply to Problem solving: Difficulty level: 700, Source: Jamboree in the Problem Solving forum “Take: x² + 5|x| + 6 = 0 Subtract 6 from both sides to get: x² + 5|x| = -6 KEY CONCEPT: x² ≥ 0 and |x| ≥ 0 for all values of x In other words, x² will always be greater than or equal to 0 And |x| will always be greater than or equal to 0, which means 5|x| will always be greater than or ...” October 7, 2018 Brent@GMATPrepNow posted a reply to TRICKY! There are n teams playing in a basketball tournam in the Problem Solving forum “Good catch regor60! A few people alerted me to this error earlier in the day, but I was on the road and couldn''t respond. Man, I must have solved the question 3 or 4 times to make sure the numbers added up, BUT I never considered the impossibility of more than one team winning every game. ...” October 7, 2018 Brent@GMATPrepNow posted a reply to Is -3*x^3 <= -3? in the Data Sufficiency forum “Target question: Is (-3)(x³) ≤ -3? This is a good candidate for rephrasing the target question. Take: (-3)(x³) ≤ -3? Divide both sides by -3 to get: x³ ≥ 1 Under what circumstance will x³ be greater than or equal to 1? Well, x³ EQUALS 1 when x = 1 So, x³ will be greater than ...” October 6, 2018 Brent@GMATPrepNow posted a reply to If x + 5 > 2 and x - 3 < 7, the value of x must be bet in the Problem Solving forum “GIVEN: x + 5 > 2 Subtract 5 from both sides of the inequality to get: x > -3 Or we can write this as -3 < x GIVEN: x - 3 < 7 Add 3 to both sides of the inequality to get: x < 10 COMBINE the inequalities to get: -3 < x < 10 Answer: A Cheers, Brent” October 6, 2018 Brent@GMATPrepNow posted a reply to Each year for 4 years, a farmer increased the number of in the Problem Solving forum “Here''s another approach: First notice that, if the number of trees increases by 1/4, then the new number is 5/4 times the original number. Let x = the # of trees in the orchard at the beginning of the 4 year period. (5/4)x = # of trees after 1 year (5/4)(5/4)x = # of trees after 2 years ...” October 5, 2018 Brent@GMATPrepNow posted a reply to Health insurance Plan A requires the insured to pay$1000 or in the Problem Solving forum
“Here''s an algebraic approach: Let T = TOTAL COST Plan A: Person pays EITHER $1000 OR 0.5T, whichever is LESS Plan B: Person pays$300 plus 20% of anything over $300. In other words, the person pays$300 + 0.2(T - 300) Since Plan A has two different scenarios, we need to test both. That ...”
October 5, 2018
Brent@GMATPrepNow posted a new topic called Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“I thought I''d start a thread featuring some of the videos from our course. This first video is one of my favorites. It covers a useful mental-math technique called Multiplying by Doubling and Halving (length 3:25) Video link: https://www.youtube.com/watch?v=D__dWwmgq2w All the best on ...”
October 5, 2018
Brent@GMATPrepNow posted a new topic called TRICKY! There are n teams playing in a basketball tournam in the Problem Solving forum
“Several teams are competing in a basketball tournament, and each team plays every other team once. Each game has exactly 1 winner and 1 loser (no ties). If 4 teams lost exactly 5 games, 5 teams won exactly 3 games, and each of the remaining teams won all of its games, what is the total number of ...”
October 5, 2018
Brent@GMATPrepNow posted a reply to Andrew bought pizzas for his swim team. Pepperoni pizzas in the Problem Solving forum
“This question illustrates the difference between the abstract math and real world math. From the given information, we''re able to create ONE equation: 13p + 17c = 184 In high school, we learned that, if we''re given 1 equation with 2 variables, we cannot find the value of either variable, so ...”
October 5, 2018
Brent@GMATPrepNow posted a reply to ||2-3|-|2-5||=? in the Problem Solving forum
“||2-3|-|2-5|| = ||-1|-|-3|| = |1-3|| = |-2| = 2 Answer: B Cheers, Brent”
October 5, 2018
Brent@GMATPrepNow posted a reply to What is the perimeter of quadrilateral Q? in the Data Sufficiency forum
“Target question: What is the perimeter of quadrilateral Q? If we recognize that each statement alone is not sufficient, we can jump straight to...... Statements 1 and 2 combined There are several quadrilaterals that satisfy BOTH statements. Here are two: Case a: rectangle Q has ...”
October 5, 2018
Brent@GMATPrepNow posted a reply to A car salesman earns a base salary of $1,000 per month plus in the Problem Solving forum “Let x = number of cars sold in 1 month So, his pay =$1000 + ($200)(n) If he earned$2,200 in February, how many cars does he have to sell in March in order to double his February earnings? If we double $2,200, we get$4,400 We need: $1,000 + ($200)(n) = $4400 Subtract$1,000 from both sides ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to If p and q are prime numbers, is pq+1 an odd number? in the Data Sufficiency forum
“Be careful, deloitte247 You haven''t used the information about p and q being prime numbers. Cheers, Brent”
October 4, 2018
Brent@GMATPrepNow posted a reply to In the figure above, A is the center of the circle, DF is 5, in the Problem Solving forum
“As you can see from my solution above, this question is a time-killer (even if you answer it correctly!!) So, if you''re running short on time, you can reduce the correct answers to two options, and make your best guess How so? IMPORTANT: the diagrams in GMAT problem solving questions are DRAWN ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to In the figure above, A is the center of the circle, DF is 5, in the Problem Solving forum
“As you can see from my solution above, this question is a time-killer (even if you answer it correctly) So, if you''re running short on time, you can reduce the correct answers to two options, and make your best guess How so? IMPORTANT: the diagrams in GMAT problem solving questions are DRAWN TO ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to In the figure above, A is the center of the circle, DF is 5, in the Problem Solving forum
“Let x = the length of AF https://i.imgur.com/pT36mTR.png This means AD = x + 5 = radius of the circle. This is convenient, because AE is also a radius of the circle. So, AE must have length x + 5 https://i.imgur.com/aLGqKow.png At this point, we can focus on the RIGHT TRIANGLE below: ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to If p and q are prime numbers, is pq+1 an odd number? in the Data Sufficiency forum
“ Given: p and q are prime numbers Target question: Is pq + 1 an odd number? This is a good candidate for rephrasing the target question. In order for pq + 1 to be odd, we need pq to be EVEN So, we COULD rephrase our target question as Is pq an even number?, but we can do even better than ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to A political candidate collected $1,749 from a fund raising in the Problem Solving forum “In order to MAXIMIZE the number of contributors, we must MINIMIZE the amount that each supporter contributes. So, let''s say that each supporter contributes exactly$50 (which is the minimum about that each supporter contributes) $50 divides into$1,749 a total of 34 times (with $49 left over). ...” October 4, 2018 Brent@GMATPrepNow posted a reply to If x^2 + 3x + 3 = 5x + 6 then x equals in the Problem Solving forum “nonplus2''s approach is the as mine, but a reasonably fast alternative approach is to test the answer choices . Answer choice A suggests that one possible solution is x = -1 So, plug x = -1 into the equation to get: (-1)² + 3(-1) + 3 = 5(-1) + 6 Simplify to get: 1 = 1. Perfect!!! So, x = -1 ...” October 4, 2018 Brent@GMATPrepNow posted a reply to A thin piece of wire 40 meters long is cut into two pieces. in the Problem Solving forum “One approach is to plug in a value for r and see what the output should be. Let''s say r = 0. That is, the radius of the circle = 0 This means, we use the entire 40-meter length of wire to create the square. So, the 4 sides of this square will have length 10, which means the area = 100 So, ...” October 4, 2018 Brent@GMATPrepNow posted a reply to The price of a phone call consists of a standard connection in the Problem Solving forum “A 10-minute call costs$2.90 and a 16-minute call costs $4.40$4.40 - $2.90 =$1.50, and 16 minutes - 10 minutes = 6 minutes So, the extra $1.50 paid for extra 6 minutes of calling So,$0.75 would pay for 3 minutes of calling How much does a 13-minute call cost? A 10-minute call costs ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to How many ounces of water must be added to 10 ounces of 3 % in the Problem Solving forum
“The original solution contains 10 ounces 3% of that is alcohol 3% of 10 = 0.3 So, the original solution contains 0.3 ounces of alcohol Let x = the amount of water (in ounces) that must be added So, the volume of the RESULTING solution = 10 + x ounces IMPORTANT: Since we''re adding water ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to Ken has a group of coins worth $6.70. He has four times as m in the Problem Solving forum “Let x = the NUMBER of dimes So, 4x = the NUMBER of nickels And 4x - 20 = the NUMBER of quarters One dime is worth$0.1, so 0.10x = the total VALUE of the dimes (in dollars) Likewise, (0.05)(4x) = the total VALUE of the nickels (in dollars) And (0.25)(4x - 20) = the total VALUE of the ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to Goku and Vegeta are waiting in a line, are there more than 1 in the Data Sufficiency forum
“Target question: Are there more than 10 people waiting in the line? Head straight to... Statements 1 and 2 combined There are several scenarios that satisfy BOTH statements. Here are two: Case a: BACK A, B, C, D, Vegeta, Picollo, Goku, E, F, G, H FRONT. In this case, the answer to the ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to Vivian drives to her sister's house and back. She takes the in the Problem Solving forum
“One approach is to assign a "nice" value (one that works well with 50 mph and 70 mph) to the distance her sister''s house. So, let''s say the distance is 350 miles Average speed = (total distance traveled)/(total travel time) TOTAL distance = 350 miles + 350 miles = 700 miles ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to Tom’s Mom is five times as old as him. In 6 years, Tom’ in the Problem Solving forum
“Tom’s Mom is five times as old as him. Let T = Tom''s PRESENT age So, 5T = Mom''s PRESENT age This also means: Let T + 6= Tom''s age IN 6 YEARS and 5T + 6 = Mom''s age IN 6 YEARS In 6 years, Tom’s Mom will be three times as old as Tom. In other words: (Mom''s age IN 6 YEARS) = ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to A “descending number” is a three-digit number, such that in the Problem Solving forum
“Let''s use some counting methods to solve this. P(selected number is "descending") = total # of descending numbers/total # of 3-digit numbers total # of 3-digit numbers 3-digit numbers go from 100 to 999 inclusive A nice rule says: the number of integers from x to y inclusive ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to Challenge question: If y < 0 < x, is x/y > -1? in the Data Sufficiency forum
“I checked the link you provided, Fabio. For me, the response from the test-makers that sticks out the most is this: "it is highly unlikely that you would come across a question with independently sufficient statements that contradict each other" I think the person answering the ...”
October 2, 2018
Brent@GMATPrepNow posted a reply to Challenge question: If y < 0 < x, is x/y > -1? in the Data Sufficiency forum
“My apologies. I posted my question without noticing its FATAL FLAW. KEY CONCEPT: On the GMAT, the two statements in a Data Sufficiency question will never contradict each other (for more on this, see the video below) Let''s examine the main issue. Statement 1: x + y > 0 Okay, so x + ...”
October 2, 2018
Brent@GMATPrepNow posted a reply to During a two-week period, the price of an ounce of silver in the Problem Solving forum
“Another approach is to test a "nice" value x A great value would be $80 (since we get$100 after we increase $80 by 25%) So, x =$80 In other words, the price of silver was $80 per ounce at the beginning of the two-week period. During a two-week period, the price of an ounce of ...” October 2, 2018 Brent@GMATPrepNow posted a new topic called Challenge question: If y < 0 < x, is x/y > -1? in the Data Sufficiency forum “If y < 0 < x, is x/y > -1? (1) x + y > 0 (2) 3x < -2y Answer: D Difficulty level: 600 - 650 Source: www.gmatprepnow.com” October 2, 2018 Brent@GMATPrepNow posted a reply to For all values of x and y , let x&y be defined by x& in the Problem Solving forum “Nice question! GIVEN: x&y = xy − x + 1 So, take the equation: (a − 2)&a = a&(a + 1) Apply rules to get the equation: (a - 2)(a) - (a - 2) + 1 = (a)(a + 1) - a + 1 Expand: a² - 2a - a + 2 + 1 = a² + a - a + 1 Simplify: a² - 3a + 3 = a² + 1 Subtract a² from both sides ...” October 2, 2018 Brent@GMATPrepNow posted a reply to If 3 different numbers are selected from the first 8 prime n in the Problem Solving forum “The first 8 prime numbers are: {2, 3, 5, 7, 11, 13, 17, 19} Notice that only one prime number is EVEN, and the remaining seven numbers are ODD. Also notice that the sum of 3 numbers will be EVEN only if one of the three selected numbers is 2 So, the question is really asking "What is the ...” October 2, 2018 Brent@GMATPrepNow posted a reply to The symbol Ω represents one of the following operations: ad in the Data Sufficiency forum “Target question: What is the value of 1 Ω 1? Given: Ω represents one of the following operations: addition, subtraction, multiplication or division. Statement 1: 2 Ω 2 = 4 2 - 2 = 0, so Ω CANNOT represent subtraction. 2 ÷ 2 = 1, so Ω CANNOT represent division. 2 + 2 = 4, so ...” October 2, 2018 Brent@GMATPrepNow posted a reply to On a 20 mile course, Pat bicycled at an average rate of 30 in the Problem Solving forum “Let''s start with a WORD EQUATION (Distance traveled at 30 mph) + (Distance traveled at 8 mph) = 20 miles Distance = (rate)(time) Let t = the time (in hours) Pat spent running at 8 mph Aside: 12 minutes = 1/5 hours So, we get: (30 miles per hour)(1/5 hours) + (8 miles per hour)(t ...” October 2, 2018 Brent@GMATPrepNow posted a reply to The greatest common factor of 16 and the positive integer n in the Problem Solving forum “Now, we can use ELIMINATION to find the correct answer. Goal: Find GCF of 210 and n. 210 = (2)(3)(5)(7) The greatest common factor of 16 and the positive integer n is 4 16 = (2)(2)(2)(2) 4 = (2)(2) So, we know for certain that the PRIME FACTORIZATION of n has TWO 2''s (and no more than ...” October 2, 2018 Brent@GMATPrepNow posted a reply to Jan lives x floors above the ground floor of a highrise in the Problem Solving forum “Let''s first convert 7 minutes to SECONDS in order to have uniform units of measurement. 7 minutes = 420 seconds Let''s start with a word equation Jan''s travel time (in seconds) WALKING down = Jan''s travel time (in seconds) via ELEVATOR + 420 seconds It takes her 30 seconds per floor to ...” October 1, 2018 Brent@GMATPrepNow posted a reply to Five letters A, P, P, L and E are listed in a row. How many in the Problem Solving forum “Here''s an approach that doesn''t require us to subtract the bad arrangements. Take the task of arranging the 5 letters and break it into stages. Stage 1: Arrange the letters A, L, E in a row We can arrange n unique objects in n! ways. So, we can arrange the 3 letters in 3! ways (= 6 ...” October 1, 2018 Brent@GMATPrepNow posted a reply to Jevan must paint 3 rooms in a house. Room A can be painted in the Problem Solving forum “Take the task of painting the 3 rooms and break it into stages. Stage 1: Select a color for Room A Room A can be painted orange, red or green So, we can complete stage 1 in 3 ways Stage 2: Select a color for Room B Room B can be painted orange, white or red. So we can complete this ...” October 1, 2018 Brent@GMATPrepNow posted a reply to Improve My Overall Score in the Last Leg of Preparation? in the GMAT Strategy forum “The resource labeled "OG2018" has questions from the 2018 OG See: https://www.beatthegmat.com/mba/official-guide-2018-library Cheers, Brent” October 1, 2018 Brent@GMATPrepNow posted a reply to Improve My Overall Score in the Last Leg of Preparation? in the GMAT Strategy forum “Look no further<i class="em em-grinning"></i> : https://www.beatthegmat.com/official-guide-question-library-t296755.html Cheers, Brent” October 1, 2018 Brent@GMATPrepNow posted a reply to If m and n are integers, is mn an odd integer? in the Data Sufficiency forum “Some important rules: #1. ODD +/- ODD = EVEN #2. ODD +/- EVEN = ODD #3. EVEN +/- EVEN = EVEN #4. (ODD)(ODD) = ODD #5. (ODD)(EVEN) = EVEN #6. (EVEN)(EVEN) = EVEN Target question: Is mn an odd integer? Given: m and n are integers Statement 1: m(n+1) is even Let''s test some ...” October 1, 2018 Brent@GMATPrepNow posted a reply to If n is an integer, is n even? in the Data Sufficiency forum “Some important rules: 1. ODD +/- ODD = EVEN 2. EVEN +/- ODD = ODD 3. EVEN +/- EVEN = EVEN 4. (ODD)(ODD) = ODD 5. (ODD)(EVEN) = EVEN 6. (EVEN)(EVEN) = EVEN Target question: Is integer n EVEN? Statement 1: n² - 1 is an odd integer n² - 1 = (n + 1)(n - 1) So, statement 1 is ...” October 1, 2018 Brent@GMATPrepNow posted a reply to When positive integer n is divided by 13, the remainder is 2 in the Problem Solving forum “When it comes to remainders, we have a nice rule that says: If N divided by D leaves remainder R, then the possible values of N are R, R+D, R+2D, R+3D,. . . etc. For example, if k divided by 5 leaves a remainder of 1, then the possible values of k are: 1, 1+5, 1+(2)(5), 1+(3)(5), ...” September 30, 2018 Brent@GMATPrepNow posted a reply to A marketing firm determined that, of 200 households surveyed in the Problem Solving forum “We can also solve this question using the Double Matrix Method. Here, we have a population of 200 households , and the two characteristics are: - using or not using Brand A soap - using or not using Brand B soap So, we can set up our matrix as follows (where "~" represents ...” September 30, 2018 Brent@GMATPrepNow posted a reply to Lindsay can paint 1/x of a certain room in 20 minutes. What in the Problem Solving forum “Given: Lindsay can paint 1/x of a certain room in 20 minutes So, in 1 HOUR, Lindsay can paint 3/x of the room Given: Lindsay and Joseph can paint the room in 1 HOUR. During that one hour, Lindsay can paint 3/x of the room. So, during that 1 HOUR, Joseph must paint the rest (whatever Lindsay ...” September 30, 2018 Brent@GMATPrepNow posted a reply to PS : In a certain clothing store in the Problem Solving forum “Let C = price of one pair of the CHEAPEST socks So, 2C - 1 = price of one pair of the MOST EXPENSIVE socks A customer notices that for exactly$18, she can buy three fewer pairs of the most expensive socks than the cheapest socks. As a word equation, we can write: (# of pairs of EXPENSIVE ...”
September 30, 2018
Brent@GMATPrepNow posted a reply to If x and y are positive integers, is x/y < (x+5)/(y+5)? in the Data Sufficiency forum
“ Given: x and y are positive integers Target question: Is x/y < (x+5)/(y+5)? This is a good candidate for rephrasing the target question. Since y is POSITIVE, we can safely take the inequality x/y < (x+5)/(y+5) and multiply both sides by y. When we do this, we get: x < ...”
September 30, 2018
Brent@GMATPrepNow posted a reply to If x is the greatest common factor of 36 and 96, what is the in the Problem Solving forum
“Mitch''s solution is the approach I''d take, but another way to answer this question is to simply LIST the factors of each value and then find the GREATEST factor they have in common. When listing factors, it''s best to do so in pairs of values with a given product (either 36 or 96). Here''s what ...”
September 30, 2018
Brent@GMATPrepNow posted a reply to If a photocopier makes 2 copies in 1313 second, then, at the in the Problem Solving forum
“We can also solve this question with equivalent ratios We''ll first convert 4 minutes to SECONDS in order to use the same units of measurement throughout the solution. 1 minute = 60 seconds So, 4 minutes = 240 seconds. Now let''s set up and equation using the ratio # of copies/time in ...”
September 30, 2018
Brent@GMATPrepNow posted a reply to A number of people each wrote down one of the first 30 posit in the Data Sufficiency forum
“Target question: Were any of the integers written down by more than one of the people? Given: A number of people each wrote down one of the first 30 positive integers. Statement 1: The number of people who wrote down an integer was greater than 40. If there were exactly 30 people, ...”
September 29, 2018
Brent@GMATPrepNow posted a reply to A computer programmer needs to print 148 documents. The in the Problem Solving forum
“We can also answer this question using a step-by-step approach based on number sense. IMPORTANT: The word approximately typically suggests that we can be somewhat aggressive with our estimation There are 148 documents and the documents have an average length of 10 pages So, the TOTAL number ...”
September 29, 2018
Brent@GMATPrepNow posted a reply to List M consists of 50 decimals, each of which has a value be in the Problem Solving forum
“Let''s examine the EXTREME CASES S - T = x percent of T So, S - T = (x/100)T Divide both sides by to get: (S - T)/T = x/100 Multiply both sides by 100 to get: x = 100(S - T)/T First, we we''ll MINIMIZE the value of x by minimizing the value of S - T and maximizing the value of T. This ...”
September 29, 2018
Brent@GMATPrepNow posted a reply to If a child flips a coin five times in a row, what is the in the Problem Solving forum
“If a coin is flipped 5 times in a row, there are 32 possible outcomes (HHTTH, HTHTT, TTTTT, etc) How did we get 32? Well, there are 2 possible outcomes for the 1st coin flip, 2 possible outcomes for the 2nd coin flip, 2 outcomes for the 3rd flip, 2 outcomes for the 4th flip, and 2 outcomes for ...”
September 29, 2018
Brent@GMATPrepNow posted a reply to R and S can complete a certain job in 6 and 4 days in the Problem Solving forum
“Let''s assign a "nice" value to the job, a value that works well with the given values (6 days and 4 days ). So, let''s say the ENTIRE job is to make 24 widgets R can complete a certain job in 6 days In other words, R can make 24 widgets in 6 days So, R can make 4 widgets per day ...”
September 28, 2018
Brent@GMATPrepNow posted a reply to An engagement team consists of a project manager, team in the Problem Solving forum
“For this question, let''s first ignore the restriction regarding the two consultants who refuse to work together and find the total number of different teams. Then we''ll determine how many of those teams break the rule about the two consultants. In other words, # of "good" teams = ...”
September 28, 2018
Brent@GMATPrepNow posted a reply to In 2004, 2,400 condos sold, 15% of the total housing units in the Problem Solving forum
“We can also solve this with a little number sense If 15% of the units sold WERE condos, then 85% of the units sold new NOT condos. GIVEN: 2,400 represents 15% of the total housing units sold that year So, 4,800 must represent 30% of the total housing units sold that year And 9,600 must ...”
September 27, 2018
Brent@GMATPrepNow posted a reply to In 2004, 2,400 condos sold, 15% of the total housing units in the Problem Solving forum
“We can solve the question with equivalent ratios If 15% of the units sold WERE condos, then 85% of the units sold new NOT condos. So we want to determine the number of sold units that represent 85% of all units sold We''ll use the ratio: (number of units sold)/(percent of units sold) Let x = ...”
September 27, 2018
Brent@GMATPrepNow posted a reply to A set of numbers has an average of 50. If the largest elemen in the Problem Solving forum
“The largest element is 4 greater than 3 times the smallest element Let x = the smallest number in the set. So, 3x + 4 = the largest number in the set. So, the set looks something like this {x, ?, ?, . . . . ?, 3x+4} The key to this question is that the AVERAGE = 50 Since all of the answer ...”
September 26, 2018
Brent@GMATPrepNow posted a reply to A set of numbers has an average of 50. If the largest elemen in the Problem Solving forum
“The largest element is 4 greater than 3 times the smallest element Let x = the smallest number in the set. So, 3x + 4 = the largest number in the set. So, the set looks something like this {x, ?, ?, . . . . ?, 3x+4} The key to this question is that the AVERAGE = 50 Since all of the answer ...”
September 26, 2018
Brent@GMATPrepNow posted a reply to The sequence Sn has the terms S1=1, S2=2, S3=6, S4=15, S5=31 in the Problem Solving forum
“If you don''t spot a pattern, you can always TEST the answer choices We want to find Sn - Sn-1 So, let''s test a value of n. How about n = 2 So, we want to find the value of S2 - S1 Well, we''re told that S2 = 2 and S1 = 1 So, S2 - S1 = 2 - 1 = 1 So, when n = 2, the answer to the ...”
September 25, 2018
Brent@GMATPrepNow posted a reply to A and B represent digits in the Problem Solving forum
“I''m not saying that 68+8=86 I''m saying that, if A=6 and B=8, then our equation (AB + B = BA) becomes 68 + 8 = 86 Since this equation is faulty, we can eliminate answer choice B Cheers, Brent”
September 24, 2018
Brent@GMATPrepNow posted a reply to W, X, Y and Z each represent a different number. If the sum in the Problem Solving forum
“KEY CONCEPT: The sum of all of the rows = The sum of all of the columns So, 3 + 6 + 9 + 0 = (-2) + 7 + n + 5 Solve: n = 8 Answer: C Cheers, Brent”
September 24, 2018
Brent@GMATPrepNow posted a reply to If x^y = 1 then what is the in the Data Sufficiency forum
“Target question: What is the value of x? Given: x^y = 1 If x^y = 1, then there are 3 possible cases: case i: x = 1, and y = any value (e.g., 1^9 = 1) case ii: x = -1, and y = an even integer (e.g., (-1)^4 = 1) case iii: x = any non-zero value, and y = 0 (e.g., 7^0 = 1) Statement ...”
September 23, 2018
Brent@GMATPrepNow posted a reply to If 893 × 78 = p, which of the following is equal to 893 × in the Problem Solving forum
“Given: 893 x 78 = P 893 x 79 = 893 x (78 + 1) = (893)(78) + (893)(1) = P + 893 = D Cheers, Brent”
September 23, 2018
Brent@GMATPrepNow posted a reply to In an office that employs 120 people, m% of the employees in the Data Sufficiency forum
“I thought I''d point out that the two approaches above are known as the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it. Here, we have a population of students, and the two characteristics ...”
September 22, 2018
Brent@GMATPrepNow posted a reply to The shaded region in the figure above represents a in the Problem Solving forum
“IMPORTANT: the diagrams in GMAT problem solving questions are DRAWN TO SCALE unless stated otherwise. So, we can use this fact to solve the question by simply "eyeballing" the diagram. See our video below on this topic as well as other assumptions we can make about diagrams on the ...”
September 21, 2018
Brent@GMATPrepNow posted a reply to Challenge question: If ∆ABC is an isosceles triangle in the Data Sufficiency forum
“Target question: What is the perimeter of ∆ABC? Given: ∆ABC is an isosceles triangle Statement 1: AB = 10√3 We only know the measurement of ONE side of the triangle. So, there''s no way to determine the triangle''s perimeter. Since we cannot answer the target question with ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to Challenge question: If ∆ABC is an isosceles triangle in the Data Sufficiency forum
“Thanks Fabio! I fixed it. Cheers, Brent”
September 20, 2018
Brent@GMATPrepNow posted a reply to If Albert can travel 200 miles in 4 hours, how many hours in the Problem Solving forum
“Another approach is to apply some number sense GIVEN: Albert can travel 200 miles in 4 hours This means: Albert can travel 100 miles in 2 hours And: Albert can travel 50 miles in 1 hour 350 miles = 200 miles + 100 miles + 50 miles So, the time to travel 350 miles = 4 hours + 2 hours + 1 ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to In four years, Andy will be twice as old as Betsy. How old in the Data Sufficiency forum
“ Given: In four years, Andy will be twice as old as Betsy. Let A = Andy''s PRESENT age Let B = Betsy''s PRESENT age So, A+4 = Andy''s age IN 4 YEARS And so, B+4 = Betsy''s age IN 4 YEARS If Andy will be twice as old as Betsy IN 4 YEARS, we can write: A+4 = 2(B+4) Expand: A + 4 = 2B + 8 ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to What is the perimeter of a rectangle? in the Data Sufficiency forum
“Target question: What is the perimeter of a rectangle? This is a good candidate for rephrasing the target question. Let x = the length of the rectangle''s base Let y = the length of the rectangle''s height So, the perimeter of the rectangle = 2x + 2y REPHRASED target question: What is the ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to How many multiples of 33 lie between 101 and 1,000, inclusiv in the Problem Solving forum
“Another approach is to apply the following rule: If x and y are multiples of k, then the number of multiples of k from x to y inclusive = So, for example, the multiples of 3 from 6 to 21 inclusive = 6 So, the number of multiples of 33 from 132 to 990 inclusive = (990 - 132)/33 + 1 = 858/33 ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to How many multiples of 33 lie between 101 and 1,000, inclusiv in the Problem Solving forum
“Some positive multiples of 33 are: 33, 66, 99, 132, 165, 198,. . . , 957, 990, 1023 So, we want the number of multiples of 33 from 132 to 990 inclusive Observe: 132 = (33)(4) 165 = (33)(5) 198 = (33)(6) . . . 957 = (33)(29) 990 = (33)(30) We can see that the number of multiples of ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to Last year's receipts from the sale of candy on Valentine's in the Problem Solving forum
“GIVEN: 385 million dollars represents 7% of TOTAL candy sales In other words: 7% of TOTAL candy sales = 385 million dollars Rewrite as: (7/100)(TOTAL candy sales) = 385 million To multiply both sides by 100/7 to get: TOTAL candy sales = (100/7)(385 million) ASIDE: We need not perform any ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to In the coordinate plane, line M travels through points in the Problem Solving forum
“KEY CONCEPT: In a straight line with slope m, any segment of the line will have slope m. To get from point (9, 10) to point (0, 4), we start at (9, 10) and move 9 spaces to the left and 6 spaces down to get to (0, 4) Let''s keep going. Starting at (0, 4), we can, once again, move 9 spaces ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to If x and y are different prime numbers, each greater than 2, in the Problem Solving forum
“Some important rules: #1. ODD +/- ODD = EVEN #2. ODD +/- EVEN = ODD #3. EVEN +/- EVEN = EVEN #4. (ODD)(ODD) = ODD #5. (ODD)(EVEN) = EVEN #6. (EVEN)(EVEN) = EVEN If x and y are different prime numbers, each greater than 2 . . . Since all prime numbers (EXCEPT 2) are ODD, this statement ...”
September 19, 2018
Brent@GMATPrepNow posted a reply to How many 3 digit numbers can we make such that two of the in the Problem Solving forum
“There are 3 cases to consider: case 1) numbers of the form XXY (1st and 2nd digits are the same and the 3rd digit is different) case 2) numbers of the form XYX (1st and 3rd digits are the same and the 2nd digit is different) case 3) numbers of the form YXX (2nd and 3rd digits are the same and the ...”
September 19, 2018
Brent@GMATPrepNow posted a reply to In 2001, John invest x dollars ina special account that in the Problem Solving forum
“ John $250 in his account in 2006 and in 2008 he has$270 in his account, So, in 2 years, John''s balance increases by $20 So, the balance increases$10 EACH YEAR In 2001, John invests x dollars in a special account that yields y% simple interest annually John''s balance increases $10 EACH ...” September 19, 2018 Brent@GMATPrepNow posted a reply to GMAT Official Guide - Probability googly in the Problem Solving forum “P(selecting a sibling pair) = P(select a junior with a sibling AND select the senior who is that junior''s sibling) = P(select a junior with a sibling) x P(select the senior who is that junior''s siblingx 1/800 = 60/800,000 = 3/40,000 = A Note: P(select a junior with a sibling) = 60/1000, ...” September 19, 2018 Brent@GMATPrepNow posted a reply to Which of the following decribes all values of n for which in the Problem Solving forum “Another approach is to test values and eliminate answer choices For example, one value of n that satisfies the equation n² - 1 ≥ 0 is n = 2 Notice that 2² - 1 = 4 - 1 = 3 and 3 ≥ 0 Now check the answer choices. . . Answer choice B says that n CANNOT equal 2 (since it says n ≤ 1) As ...” September 19, 2018 Brent@GMATPrepNow posted a reply to In the figure above, what is the distance from point P to in the Problem Solving forum “Once we create our right triangle with sides 1/2, 1/2 and x (the hypotenuse), we can apply the Pythagorean Theorem to get: (1/2)² + (1/2)² = x² Expand: 1/4 + 1/4 = x² So, 1/8 = x² This means x = √(1/8) Check the answer choices. . . .√(1/8) is not there. Looks like we need to simplify ...” September 19, 2018 Brent@GMATPrepNow posted a reply to If six coins are flipped simultaneously, the probability of in the Problem Solving forum “When it comes to probability questions involving "at least," it''s best to try using the complement. That is, P(Event A happening) = 1 - P(Event A not happening) So, here we get: P(getting at least one heads and at least one tails) = 1 - P(not getting at least one heads and at least one ...” September 19, 2018 Brent@GMATPrepNow posted a reply to If n is an integer, is n(n+2) divisible by 8? in the Data Sufficiency forum “Target question: Is n(n+2) divisible by 8? Statement 1: n is an even number. Let''s examine some CONSECUTIVE even numbers: 6, 8, 10, 12, 14, 16, 18, 20, 22, etc Notice that the numbers increase by 2 with each subsequent value. So, if n is EVEN, then we know that n+2 is also even. Also, ...” September 19, 2018 Brent@GMATPrepNow posted a new topic called Challenge question: If ∆ABC is an isosceles triangle in the Data Sufficiency forum “If ∆ABC is an isosceles triangle, what is the perimeter of ∆ABC? (1) AB = 10√3 (2) AC = 8 Answer: C Difficulty level: 600 - 650 Source: www.gmatprepnow.com” September 19, 2018 Brent@GMATPrepNow posted a reply to Challenge question: If 40 percent more than 40 percent of x in the Problem Solving forum “--------ASIDE-------------------- 40% MORE THAN k = k + (40% of k) = k + 0.4x = 1.4x 40% LESS THAN Q = Q - (40% of Q) = Q - 0.4Q = 0.6Q ----NOT ONTO THE QUESTION!!----------- 40 percent of x is the same as 0.4x So, 40 percent more than 40 percent of x is the same as (1.4)(0.4x) ...” September 18, 2018 Brent@GMATPrepNow posted a reply to In how many ways a cricket team consisting of 5 batsmen, 4 in the Problem Solving forum “Take the task of creating a cricket team and break it into stages. Stage 1: Select 5 batsmen Since the order in which we select the batsmen does not matter, we can use combinations. We can select 5 batsmen from 7 batsmen in 7C5 ways (21 ways) So, we can complete stage 1 in 21 ways ...” September 18, 2018 Brent@GMATPrepNow posted a reply to Which of the following functions satisfies f(a+b)=f(a)f(b) f in the Problem Solving forum “Another approach is to a = 1 and b = 1 So, with each function, is it true that f(1 + 1) = f(1)f(1)? In other words, is it true that f(2) = f(1)f(1)? A. f(x) = x + 1 Is it true that f(2) = f(1)f(1)? Plug values into the function to get: 2 + 1 = (1 + 1)(1 + 1) Simplify: 3 = 4 No good. ...” September 18, 2018 Brent@GMATPrepNow posted a reply to a and b are positive numbers. What is the value of (a-b)/(a+ in the Data Sufficiency forum “Target question: What is the value of (a - b)/(a + b)? Statement 1: a = 2b Take: (a - b)/(a + b) Replace a with 2b to get: (2b - b)/(2b + b) Simplify: b/3b Divide top and bottom by b to get: 1/3 So, the answer to the target question is (a - b)/(a + b) = 1/3 Since we can answer the ...” September 18, 2018 Brent@GMATPrepNow posted a reply to Which of the following functions satisfies f(a+b)=f(a)f(b) f in the Problem Solving forum “Upon scanning the answer choices, we might recognize that answer choice E, f(x) = 2^x, involves a variable exponent and that the given information that f(a+b) = f (a)f(b) looks A LOT like the Product Law: (k^a)(k^b) = k^(a+b) So, let''s check E first. E. f(x) = 2^x If f(x) = 2^x, then f(a) = ...” September 18, 2018 Brent@GMATPrepNow posted a reply to A certain business school has a student body of 2,000 studen in the Data Sufficiency forum “I thought I''d point out that Jay''s approach is also known as the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it. Here, we have a population of students, and the two characteristics are: ...” September 18, 2018 Brent@GMATPrepNow posted a reply to Going in to the last game of his basketball season, Adrian in the Problem Solving forum “Let G = total number of games that Adrian played in the ENTIRE season Going in to the last game of his basketball season, Adrian had averaged 24 points per game. At this point, Adrian has played G-1 games So, we can write: (total number of points in G-1 games)/(G-1) = 24 Multiply both sides ...” September 17, 2018 Brent@GMATPrepNow posted a new topic called Challenge question: If 40 percent more than 40 percent of x in the Problem Solving forum “If 40 percent more than 40 percent of x is equal to 40 percent less than y, what is the value of x/y? A) 3/8 B) 15/16 C) 1 D) 15/14 E) 15/4 Answer: D Difficulty level: 600 – 650 Source: www.gmatprepnow.com” September 17, 2018 Brent@GMATPrepNow posted a reply to What is the perimeter of isosceles triangle LMN? 1) Side LM in the Data Sufficiency forum “Target question: What is the perimeter of isosceles triangle LMN? Jump to. . . . Statements 1 and 2 combined There are two triangles that satisfy BOTH statements. They are: Case a: The side lengths of triangle LMN are 4, 4 and 4√2. In this case, the answer to the target question is ...” September 17, 2018 Brent@GMATPrepNow posted a reply to 2^p/2^q=? in the Data Sufficiency forum “Target question: What is the value of (2^p)/(2^q) ? This is a good candidate for rephrasing the target question. Aside: Here’s a video with tips on rephrasing the target question: Take: (2^p)/(2^q) Apply the Quotient law to get: 2^(p - q) This means (2^p)/(2^q) = 2^(p - q) So, in order ...” September 17, 2018 Brent@GMATPrepNow posted a reply to Counting question in the Ask the Test Maker forum “Good catch! (someone else just alerted me to my error) I have edited my response accordingly. Cheers, Brent” September 17, 2018 Brent@GMATPrepNow posted a reply to If 4x − 3y = 13 and 5x + 2y = −1, then x = in the Problem Solving forum “Given: 4x − 3y = 13 5x + 2y = −1 Take the top equation and multiply both sides by 2 Take the bottom equation and multiply both sides by 3 We get: 8x − 6y = 26 15x + 6y = −3 Add the two equations to get: 23x = 23 Solve: x = 1 Answer: C Cheers, Brent” September 17, 2018 Brent@GMATPrepNow posted a reply to If the ratio of the present age of Anna and Paula is 3:4 in the Problem Solving forum “Here''s a nice property of fractions: If a, b and k are positive, then (a + k)/(b + k) approaches 1 as k gets bigger. For example, the fraction (2+11)/(3+11) is closer to 1 than 2/3 is. Likewise, the fraction (1+7)/(2+7) is closer to 1 than 1/2 is. Let A = Anna''s present age Let P = Paula''s ...” September 16, 2018 Brent@GMATPrepNow posted a new topic called If x^y = 1 then what is the in the Data Sufficiency forum “If x^y = 1, then what is the value of x? (1) x < 0 (2) y is even integer” September 16, 2018 Brent@GMATPrepNow posted a reply to When Leo imported a certain item, he paid a 7 percent import in the Problem Solving forum “Here''s a step-by-step algebraic solution. Let T = the TOTAL value of the item. Leo paid a 7% import tax on the portion of the total value of the item in EXCESS of$1000 So, Leo pays tax on the amount that''s GREATER then $1000 So, Leo pays 7% tax on (T - 1000) We can write: import tax = ...” September 16, 2018 Brent@GMATPrepNow posted a reply to A rectangular-shaped carpet remnant that measures x feet in the Problem Solving forum “Area of rectangle = (base)(height) = (x feet)(y feet) = xy square feet GIVEN: 9 square feet = 1 square yard So, we can also say that 1 square foot = 1/9 square yards So, xy square feet = xy/9 square YARDS So, if xy/9 square YARDS cost$50, then each square YARD = $50/(xy/9) = ...” September 16, 2018 Brent@GMATPrepNow posted a reply to Bob drives at an average rate of 50 mph from Berkeley to Los in the Problem Solving forum “As the others have shown, the fast approach is to recognize that: travel time = distance/speed = 350/50 = 7 hours However, we could also (if necessary) solve this by applying some common sense. Bob''s speed is 50 miles per hour. In other words, for every 1 hour that elapses, Bob travels 50 ...” September 16, 2018 Brent@GMATPrepNow posted a reply to At what speed was Erik running when he was at the halfway in the Data Sufficiency forum “IMPORTANT: The two statements essentially provide the exact same information. If it took Erik 2 hours to travel 10 miles, we can conclude that his average speed was 5 miles per hour. When the two statements provide the same information in a Data Sufficiency question, the correct answer must be ...” September 15, 2018 Brent@GMATPrepNow posted a reply to Probability from GMAT prep in the Problem Solving forum “The two approaches shown above are the best (faster) approaches, but here''s one more. Since there are so few objects involved (5 apples), we should be able to quickly answer the question by simply listing and counting Let A, B, C, D, and E represent the 5 apples, and let E represent the ...” September 15, 2018 Brent@GMATPrepNow posted a reply to A zebra must get water from either a stream or pond. Which in the Data Sufficiency forum “Unfortunately, we don''t know if the two ''constant rates'' that are mentioned are the same OR not, so there''s no way to gauge the relative distances to the stream and pond. IF the two rates are equal, then the distances of the two water sources would be the same. [/quote] Even if the ...” September 14, 2018 Brent@GMATPrepNow posted a reply to A zebra must get water from either a stream or pond. Which in the Data Sufficiency forum “Target question: Which of the two sources of water is closer to the zebra’s current position? Jump straight to.... Statements 1 and 2 COMBINED There are several scenarios that satisfy BOTH statements. Here are two: Case a: When traveling to the STREAM, the zebra heads EAST in a ...” September 14, 2018 Brent@GMATPrepNow posted a reply to Taking the GMAT in four days. Need advice calming my nerves in the GMAT Strategy forum “You''re certainly not the first person to get nervous during this high-stakes (and expensive) test! If you''re interested, we have a free video on the topic on overcoming test anxiety: [url]http://www.gmatprepnow.com/module/general-gmat-strategies/video/1252[/url] Also, as part of managing ...” September 14, 2018 Brent@GMATPrepNow posted a reply to If 1/n(n+1) = 1/n – 1/(n+1), then what is the value of 1/( in the Problem Solving forum “If 1/n(n+1) = 1/n – 1/(n+1), then... 1/(1*2) = 1/1 - 1/2 1/(2*3) = 1/2 - 1/3 1/(3*4) = 1/3 - 1/4 . . . 1/(98*99) = 1/98 - 1/99 1/(99*100) = 1/99 - 1/100 So, 1/(1*2) + 1/(2*3) + 1/(3*4) + … + 1/(99*100) = (1/1 - 1/2) + (1/2 - 1/3) + (1/3 - 1/4) + . . . (1/98 - 1/99) + (1/99 - ...” September 14, 2018 Brent@GMATPrepNow posted a reply to Is x < 0? in the Data Sufficiency forum “Target question: Is x < 0? Statement 1: |x| = -x Let''s TEST some values. There are several values of x that satisfy statement 1. Here are two: Case a: x = -1. Notice that |-1| = -(-1). In this case, the answer to the target question is YES, x IS less than 0 Case b: x = 0. Notice that ...” September 14, 2018 Brent@GMATPrepNow posted a reply to If n is an integer, is (n+1)^2 an even integer? in the Data Sufficiency forum “Some important rules: 1. ODD +/- ODD = EVEN 2. ODD +/- EVEN = ODD 3. EVEN +/- EVEN = EVEN 4. (ODD)(ODD) = ODD 5. (ODD)(EVEN) = EVEN 6. (EVEN)(EVEN) = EVEN Target question: Is (n+1)² an even integer? This is a good candidate for rephrasing the target question. Aside: Here’s a video ...” September 13, 2018 Brent@GMATPrepNow posted a reply to Jack bought five mobiles at an average price of$150. The in the Problem Solving forum
“Jack bought five mobiles at an average price of $150. So, (sum of all 5 mobiles)/5 =$150 Multiply both sides by 5 to get: sum of all 5 mobiles = $750 The median of all the prices is$200. Let a = smallest value Let b = 2nd smallest value Let d = largest value Let c = 2nd largest value ...”
September 13, 2018
Brent@GMATPrepNow posted a reply to A driver paid n dollars for auto insurance for the year in the Problem Solving forum
“First recognize that INCREASING a value by p percent is the same as multiplying by (100 + p)/100 For example, increasing a value by 7% is the same as multiplying by (100 + 7)/100 Likewise, increasing a value by 25% is the same as multiplying by (100 + 25)/100 Also, recognize that DECREASING a ...”
September 13, 2018
Brent@GMATPrepNow posted a reply to To furnish a room in a model home, an interior decorator is in the Problem Solving forum
“Total # of combinations = (# of ways to select 2 chairs)(# of ways to select 2 tables) So, 150 = (# of ways to select 2 chairs)(# of ways to select 2 tables) # of ways to select 2 chairs 5 tables, choose 2 of them. Since the order of the selected chairs does not matter, we can use ...”
September 13, 2018
Brent@GMATPrepNow posted a reply to How many positive two-digit numbers yield a remainder of 1 in the Problem Solving forum
“When it comes to remainders, we have a nice rule that says: If N divided by D leaves remainder R, then the possible values of N are R, R+D, R+2D, R+3D,. . . etc. For example, if k divided by 5 leaves a remainder of 1, then the possible values of k are: 1, 1+5, 1+(2)(5), 1+(3)(5), ...”
September 13, 2018
Brent@GMATPrepNow posted a reply to good farming (OG13 71) in the Sentence Correction forum
“(A) good growing conditions both encouraged farming traditions that, in places, endure in The word COMBINATION implies that the two conditions combine to have an effect. So, the word BOTH is redundant. ELIMINATE A (B) good growing conditions encouraged farming traditions that have, in places, ...”
September 12, 2018
Brent@GMATPrepNow posted a reply to What is the biggest positive integer which will always divid in the Problem Solving forum
“One approach is to list integers in the form n, n+1 and n+2 such that n is even, and look for a pattern... 2, 3, 4 Product = 24, which is divisible by 2, 3, 6, 12 and 24 4, 5, 6 Product = 120, which is divisible by 2, 3, 6, 12 and 24 6, 7, 8 Product = 336, which is divisible by 2, 3, 6, ...”
September 12, 2018
Brent@GMATPrepNow posted a reply to If the interior angles of a triangle are in the ratio 3 to in the Problem Solving forum
“Oops, good catch! I have edited my response accordingly. Cheers and thanks, Brent”
September 12, 2018
Brent@GMATPrepNow posted a reply to Flor is choosing three of five colors of paint to use for he in the Problem Solving forum
“Jay''s approach is the approach that I''d typically use. However, it''s important to note that, when the answer choices are so small (as they are here), we should also consider the straightforward strategy of listing and counting Let R, B, P, G and Y represent the colors Red, Blue, Purple, Green ...”
September 12, 2018
Brent@GMATPrepNow posted a reply to If the interior angles of a triangle are in the ratio 3 to in the Problem Solving forum
“All 3 angles must add to 180° So, if we divide 180° into 3 angles in the ratio 3 : 4 : 5, we get: 45° : 60° : 75° What is the measure of the largest angle? The largest angle is 75 degrees° Answer: D Cheers, Brent”
September 12, 2018
Brent@GMATPrepNow posted a reply to Is p + pz = p? in the Data Sufficiency forum
“Target question: Is p + pz = p? This is a great candidate for rephrasing the target question. Aside: Here’s a video with tips on rephrasing the target question: Take Is p + pz = p? and subtract p from both sides to get: Is pz = 0? In order for pz to equal 0, it must be the case that ...”
September 12, 2018
Brent@GMATPrepNow posted a reply to A company plans to assign identification numbers to its in the Problem Solving forum
“Take the task of creating the identification numbers and break it into stages. Stage 1: Select the first digit of the identification number The first digit can be 1, 2, 3, 4, 5, 6, 7, 8, or 9 So, we can complete stage 1 in 9 ways Stage 2: Select the second digit of the identification ...”
September 12, 2018
Brent@GMATPrepNow posted a reply to Last week Chris earned x dollars per hour for the first 40 in the Problem Solving forum
“If Chris worked 48 hours, then he was paid 40x dollars for first 40 hours and (8)(22) dollars for the next 8 hours Since Chris earned $816, we can write: 40x + (8)(22) = 816 Simplify: 40x + 176 = 816 Subtract 176 from both sides: 40x = 640 Solve: x = 640/40 = 16 Answer: D Cheers, Brent” September 11, 2018 Brent@GMATPrepNow posted a reply to If x is even integer, which of the following must be an odd in the Problem Solving forum “A quick approach is the plug in a even number for x and see what happens. A super easy number to use us x = 0 We get..... A) (3)(0)/2 = 0, which is NOT odd. ELIMINATE A. B) (3)(0)/2 + 1 = 1, which IS odd. KEEP B. C) (3)(0)² = 0, which is NOT odd. ELIMINATE C. D) (3)(0²)/2 = 0, which ...” September 11, 2018 Brent@GMATPrepNow posted a reply to The perimeter of a rectangular garden is 360 ft. What is the in the Data Sufficiency forum “Great research, Mitch! I can''t imagine there are many official questions that hinge entirely on that one (somewhat esoteric) construct. I mean, for the every question you cited, it doesn''t matter which side we call the length or the width. The correct answer is the same in all cases. It''s ...” September 11, 2018 Brent@GMATPrepNow posted a reply to The perimeter of a rectangular garden is 360 ft. What is the in the Data Sufficiency forum “Interesting. I''ve never heard of that construct. So, for a box with dimensions 3 x 4 x 5, then the side with length 5 is the length? Which dimension is the width? What about cases when the terms base and height are used? Which one is the base? In a way, this reminds me of the times when ...” September 11, 2018 Brent@GMATPrepNow posted a reply to The aerth travels around the sun at a speed of approximately in the Problem Solving forum “Another way to deal with calculating (18.5)(3600) is to use the answer choices to our advantage. First off, there''s a nice rule that says: AB = (2A)(0.5B) This strategy (which is covered in this video: https://www.gmatprepnow.com/module/general-gmat-strategies/video/1113) can sometimes save us ...” September 11, 2018 Brent@GMATPrepNow posted a reply to What is the value of 22C19? in the Problem Solving forum “Good point! I should have mentioned that I use a shortcut for calculating combinations that allows me to perform most calculations in my head. For example, for 22C3, I write the first 3 values of 22! in the numerator, and I write the 3! in the denominator So, 22C3 = (22)(21)(20)/(3)(2)(1) ...” September 11, 2018 Brent@GMATPrepNow posted a reply to What is the value of 22C19? in the Problem Solving forum “When calculating combinations, it''s sometime useful to apply the following rule: nCr = nC(n-r). In other words, "n choose r" is equal to "n choose n - r" So, for example: 10C7 = 10C3 12C9 = 12C3 8C7 = 8C1 etc. Here''s why this property works: Let''s say you have 22 ...” September 11, 2018 Brent@GMATPrepNow posted a reply to The perimeter of a rectangular garden is 360 ft. What is the in the Data Sufficiency forum “To my test-prep colleagues. I have to say that I''m a little surprised by the official answer (D). For statement 2, it could be the case that length = 120 and width = 60, OR it could be the case that length = 60 and width = 120 The assumption here is that the length of a rectangle must be ...” September 11, 2018 Brent@GMATPrepNow posted a reply to Which of the following points could lie in the same quadrant in the Problem Solving forum “Let''s test some coordinates... How about: a = 1 and b = -2. This means the point (a, b) = (1, -2), which is in QUADRANT IV Now plug a = 1 and b = -2 into each answer choice... A) (-b, -a) = -2), -1] = (2, -1), which is also in QUADRANT IV PERFECT! Answer: A Cheers, Brent” September 11, 2018 September 10, 2018 Brent@GMATPrepNow posted a reply to The sum of the ages of Doris and Fred is y years. If Doris in the Problem Solving forum “Let F = Fred''s PRESENT age Doris is 12 years older than Fred. In other words, Doris'' age = F + 12. So, the sum of their ages = F + (F + 12) Simplify to get: sum of their ages = 2F + 12 The sum of the ages = y 2F + 12 = y Now solve for Fred''s age (F). Start with: 2F + 12 = y ...” September 10, 2018 Brent@GMATPrepNow posted a reply to In the figure, ABCD is a square, and all the dots are in the Problem Solving forum “If the vertical or horizontal distance between two adjacent dots is 3 units, then the square has dimensions 12 by 12 So, the area of the ENTIRE SQUARE = (12)(12) = 144 Now, notice that the square is comprised of 32 identical triangles https://i.imgur.com/mHC9rOY.png Since 16 of the triangles ...” September 10, 2018 Brent@GMATPrepNow posted a reply to Is xy>0? in the Data Sufficiency forum “Target question: Is xy > 0? Statement 1: x³y > 0 Since x² is POSITIVE, we can safely divide both sides of the inequality by x² When we do this, we get xy > 0 So, the answer to the target question is YES, xy IS greater than 0 Since we can answer the target question with ...” September 10, 2018 Brent@GMATPrepNow posted a reply to If the circle above has center O and circumference 18π, the in the Problem Solving forum “The circle has circumference 18π circumference = (2)(radius)(π) So, (2)(radius)(π) = 18π Solve to get: radius = 9 So, OR = 9 and OT = 9 Now, we''ll deal with arc RST Here the sector angle = 60° 60°/360° = 1/6 So, the arc RST represents 1/6 of the ENTIRE circle Since the ENTIRE ...” September 10, 2018 Brent@GMATPrepNow posted a reply to Any decimal that has only a finite number of nonzero digits in the Data Sufficiency forum “Target question: Is r/s a terminating decimal? Statement 1: 90 < r < 100 There are several pairs of values that meet this condition. Here are two: Case a: r = 91 and s = 2, in which case r/s = 91/2 = 45.5 = a terminating decimal Case b: r = 91 and s = 3, in which case r/s = 91/3 = ...” September 10, 2018 Brent@GMATPrepNow posted a reply to In a certain pond, 50 fish were caught, tagged, and returned in the Problem Solving forum “We can use equivalent ratios here. We''re told that the proportion of tagged fish in the 50-fish SAMPLE is equal to the the proportion of tagged fish in the ENTIRE pond. So, (# tagged fish in SAMPLE)/50 = (total # tagged fish)/(total # of fish in POND) Let x = # of fish in the entire ...” September 10, 2018 Brent@GMATPrepNow posted a reply to permutation/combination in the Problem Solving forum “This question is a little too ambiguous to be an official GMAT question. Let''s say X, Y and Z represents 3 different songs. Is an album with song X first, song Y second and song Z third considered DIFFERENT FROM an album with song Z first, song X second and song Y third? The answer to this ...” September 9, 2018 Brent@GMATPrepNow posted a reply to Sam's car was fined when he gave Joe and Peter a ride, so in the Problem Solving forum “Hey Mitch, I think you answered the question "What was the cost of the fine?" (which IS, indeed,$48), but we''re asked to determine the dollar amount that Sam paid (= $20). Cheers, Brent” September 9, 2018 Brent@GMATPrepNow posted a reply to On Monday morning a certain machine ran continuously at a un in the Data Sufficiency forum “Here''s a similar question to practice with: https://www.beatthegmat.com/on-wednesday-morning-a-fortune-cookie-machine-ran-t301683.html Cheers, Brent” September 9, 2018 Brent@GMATPrepNow posted a reply to Sam's car was fined when he gave Joe and Peter a ride, so in the Problem Solving forum “Let F = the total cost of the fine Joe paid$3 more than 1/4 of the fine So, F/4 + 3 = the amount Joe paid Peter paid $3 less than 1/3 of the fine So, F/3 - 3 = the amount Peter paid Sam paid$4 less than 1/2 the fine So, F/2 - 4 = the amount Sam paid (amount Joe paid) + (amount Peter ...”
September 8, 2018
Brent@GMATPrepNow posted a reply to What is the area of a triangle with the following vertices in the Problem Solving forum
“Now that you know the technique, you can practice your speed with this one: http://www.beatthegmat.com/coordinate-geometry-t116975.html Cheers, Brent”
September 8, 2018
Brent@GMATPrepNow posted a reply to In the xy-plane, the line k passes through the origin and in the Data Sufficiency forum
“Target question: Is b (the y-coordinate of the point on the line) positive? Given: Line k passes through the origin and through the point (a,b) Statement 1: The slope of line k is negative There are several lines and points that satisfy statement 1. Here are two: Case a: ...”
September 8, 2018
Brent@GMATPrepNow posted a reply to Out of 2 broken TV sets and 6 fixed TV sets in Joe's Fix-My- in the Problem Solving forum
“There are 8 TV''s in total 2 are broken 6 are fixed We want to find P(at least one TV is broken) When it comes to probability questions involving at least, it''s often best to try using the complement. That is, P(Event A happening) = 1 - P(Event A not happening) So, here we get: P(getting ...”
September 8, 2018
Brent@GMATPrepNow posted a reply to what percent were stockholders who were not employees? in the Problem Solving forum
“Let''s use the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it (aka overlapping sets questions). Here, we have a population of attendees, and the two characteristics are: - stockholder ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to Geometry and Angles (My weakness) in the Problem Solving forum
“Here''s an idea of what''s going on.... https://i.imgur.com/Deg4te0.png When we compare the big triangle with the BASE 30-60-90 special triangle (which you must memorize for test day!), we can see that the hypotenuse of the big triangle is 35 times as long as the hypotenuse of the base triangle. ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to Digging in sediments in northern China, evidence has been in the Sentence Correction forum
“Important: When a sentence begins with a with noun modifier (as it does in the above sentence), stop at the comma and ask the question that the modifier raises. So, once we read, Digging in sediments in northern China, we should stop and ask . . . "Who or what was digging in ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to OG City Council Member Q in the Critical Reasoning forum
“PREMISE: Electricity demands increase 1.5% per year PREMISE: No space to build more power plants CONCLUSION: We must use LESS electricity through ordinances Strategy #1: Try to think of an assumption that''s required for the conclusion to logically follow from the premises. Notice that ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to Working simultaneously and independently at an identical con in the Problem Solving forum
“Let''s assign a nice value to x (a value that will work well with all of the numbers 3, 4 and 6. Let''s say x = 24 GIVEN: 4 machines make x units in 6 days This means 4 machines make 24 units in 6 days So, 4 machines make 4 units in 1 day So, 1 machine makes 1 unit in 1 day From here, ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to What is the value of the 2-digit positive integer n if its in the Data Sufficiency forum
“Target question: What is the value of the 2-digit positive integer n Given: Its tens digit is four times its units digit This is VERY LIMITING information. In fact, this tells us that EITHER n = 41 OR n = 82 There are no other possible values of n. Statement 1: n is an even number ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to A refrigerator holds a number of apples, bananas, carrots an in the Data Sufficiency forum
“Be careful. If you feel that the ratio A : B : C : D = 2x : 5x : 3x : 7x, then you''d be able to answer the target question WITHOUT using any statements. Cheers, Brent”
September 7, 2018
Brent@GMATPrepNow posted a reply to Which of the following points is the intersection between in the Problem Solving forum
“KEY CONCEPT: The point of intersection (call P) of the lines y = 3x + 6 and y = -2x - 4 will be such that the x- and y-coordinates of P will satisfy BOTH equations. Since both equations are set equal to y, we can write: 3x + 6 = -2x - 4 Add 2x to both sides: 5x + 6 = - 4 Subtract 6 from both ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to If a mixture of ground meat consists of 2 pounds of veal in the Problem Solving forum
“We can use the WEIGHTED AVERAGE formula: Weighted average of groups combined = (group A proportion)(group A average) + (group B proportion)(group B average) + (group C proportion)(group C average) + ... When we COMBINE the meats, the TOTAL weight = 2 + 5 = 7 pounds. So, veal comprises 2/7 of ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to Last year the price per share of Stock X increased by k in the Problem Solving forum
“One approach is to plug in values. Let $100 be the original price per share of Stock X Choose a "nice" value for k. How about k = 200 So, after a 200% increase, the new price per share =$300 Let $100 be the original earnings per share of Stock X Choose a "nice" ...” September 6, 2018 Brent@GMATPrepNow posted a reply to If 3x + 2y = -2z, what is x? in the Data Sufficiency forum “Target question: What is the value of x? Given: 3x + 2y = -2z Notice that the two statements have the variables all on the left side of the equation. So, let''s rearrange our given equation to look the same. Take: 3x + 2y = -2z Add 2z to both sides to get: 3x + 2y + 2z = 0 Statement ...” September 6, 2018 Brent@GMATPrepNow posted a reply to The selling price of an article is equal to the cost of the in the Data Sufficiency forum “Let C = cost of article Target question: The markup on a certain television set is what percent of the selling price? Statement 1: The markup on the television set is 25 percent of the cost. If C = cost of article, markup = 0.25C Selling price = cost + markup = C + 0.25C = 1.25C So, ...” September 6, 2018 Brent@GMATPrepNow posted a reply to Last year, a certain public transportation system sold an in the Problem Solving forum “The word "closest" suggests that we can use some estimation here. Let''s first estimate the number of tickets sold PER WEEK 41,000 tickets per day on weekdays (5)(41,000) = 205,000 18,000 tickets per day on weekends (2)(18,000) = 36,000 So, total tickets sold PER WEEK = ...” September 5, 2018 Brent@GMATPrepNow posted a reply to In the xy-coordinate system, line k has slope 1/2 and passes in the Problem Solving forum “While a sample size of 28 might not be a large enough to make prove/validate my recommendations, I can tell you that, from my experience, the correct answer to these kinds of questions is typically closer to E than to A. That said, if it were the case that, with this question type, the correct ...” September 5, 2018 Brent@GMATPrepNow posted a reply to In the figure above, what is the perimeter of rectangle ABPQ in the Data Sufficiency forum “Target question: What is the perimeter of rectangle ABPQ? Statement 1: The area of rectangular region ABCD is 3 times the area of rectangular region ABPQ. Since we aren''t given any information regarding ACTUAL lengths, we cannot determine the perimeter of rectangle ABPQ Since we cannot ...” September 5, 2018 Brent@GMATPrepNow posted a reply to The numbers x and y are NOT integers. The value of x is in the Data Sufficiency forum “Target question: The value of x is closest to which integer? Let''s head straight to........... Statements 1 and 2 combined There are several values of x and y that satisfy BOTH statements. Here are two: Case a: x = 2.4 and y = 1.4. These values satisfy both statements. In this case, ...” September 5, 2018 Brent@GMATPrepNow posted a reply to An insurance company sells only one type of health and one in the Data Sufficiency forum “Let H = the number of health insurance policies Let L = the number of life insurance policies Let p = the monthly premium on a life insurance policy So, 80H + pL = 5000 Target question: What is the value of p? Statement 1: The total revenue from health insurance premiums was 4/5 of ...” September 5, 2018 Brent@GMATPrepNow posted a reply to 8 cities, including Memphis, are finalists to be chosen to in the Data Sufficiency forum “Target question: What is the probability that Memphis is not chosen? ASIDE: At first glance, it may seem like we already have enough information the answer the target question. After all, if there are 8 cities, then P(Memphis is chosen) = 1/8, which means Memphis is not chosen) = 7/8, right? ...” September 5, 2018 Brent@GMATPrepNow posted a reply to In the xy-coordinate system, line k has slope 1/2 and passes in the Problem Solving forum “Let''s first determine the equation of line k A quick approach is the write the equation of line k in slope y-intercept form: y = mx + b, where m = slope and b = y-intercept. We''re told that the slope = 0.5 and the point (0,5) tells us that the y-intercept is 5 So, the equation of line k is: ...” September 5, 2018 Brent@GMATPrepNow posted a reply to A certain company assigns employees to offices in such a way in the Problem Solving forum “ASIDE: When the answer choices are small, you should also consider listing and counting Let X, Y and Z be the 3 employees. Let A and B be the 2 offices. We''ll list the possible outcomes as follows: (employees in office A | employees in office B) So, we get: ( XYZ | -- ) ( XY |Z ) ( XZ ...” September 5, 2018 Brent@GMATPrepNow posted a reply to A certain company assigns employees to offices in such a way in the Problem Solving forum “Let X, Y and Z be the 3 employees. Let A and B be the 2 offices. Take the task of assigning the employees and break it into stages. Stage 1: Assign employee X to an office There two options (office A or office B), so we can complete stage 1 in 2 ways Stage 2: Assign employee Y to an ...” September 5, 2018 Brent@GMATPrepNow posted a reply to A baker makes chocolate cookies and peanut cookies. His in the Problem Solving forum “We''re looking for the smallest possible number of chocolate chip cookies. So, let''s start by testing answer choice A A) If we make 7 chocolate chip cookies, then the remaining 88 cookies are peanut cookies. We''re told that peanut cookies are baked in batches of 6 However, 88 is NOT ...” September 4, 2018 Brent@GMATPrepNow posted a reply to If x and y are integers, what is the least possible positive in the Problem Solving forum “Another approach: There''s a nice rule that says: If j, k and d are integers, and j is a multiple of d, and k is a multiple of d, then (j+k) must be a multiple of d 21x is a multiple of 7 (since 21x = 7(3x) 35y is a multiple of 7 (since 35y = 7(5y) Since 21x and 35y are multiples of 7, the ...” September 4, 2018 Brent@GMATPrepNow posted a reply to If x and y are integers, what is the least possible positive in the Problem Solving forum “21x + 35y = 7(3x + 5y) Since x and y are INTEGERS, we know that 3x and 5y are each INTEGERS, which means 3x + 5y equals some integer So, we can write: 21x + 35y = 7(some integer) In other words, 21x + 35y is a multiple of 7 Check the answer choices.....only D is a multiple of 7 Answer: D ...” September 4, 2018 Brent@GMATPrepNow posted a reply to standard deviation in the Data Sufficiency forum “Target question: Is the standard deviation of the set positive? KEY CONCEPT: If all of the numbers in a set are EQUAL, then the standard deviation = 0 If the numbers in a set are NOT all equal, then the standard deviation > 0 Given: The set consists of a certain number of even integers ...” September 4, 2018 Brent@GMATPrepNow posted a reply to permutation/combination in the Problem Solving forum “Here''s an algebraic solution... Let M = TOTAL number of men (including Mr. Smith) at the party Let W = TOTAL number of women (including Mrs. Smith) at the party Since Mr. Smith does not shake hands with HIMSELF, Mr. Smith shakes hands with M-1 men, and he shakes hands with W women Since ...” September 4, 2018 Brent@GMATPrepNow posted a reply to Andrew has a certain number of coins in his pocket. He has in the Problem Solving forum “Let x = number of QUARTERS in pocket So, 0.25x = VALUE of quarters in pocket He has three times as many dimes as quarters So, 3x = number of DIMES in pocket So, 0.10(3x) = 0.3x = VALUE of dimes in pocket He has six times as many nickels as dimes. So, (6)(3x) = number of NICKELS in ...” September 4, 2018 Brent@GMATPrepNow posted a reply to Triathlete Dan runs along a 2-mile stretch of river and then in the Problem Solving forum “Average speed = (total distance)/(total time) We know the total distance = 4 miles The total time consists of two parts: Let''s begin with a "word equation" TOTAL time = (time spent running) + (time spent swimming) time = distance/speed So, time spent running = 2/10 = 1/5 hours ...” September 4, 2018 Brent@GMATPrepNow posted a reply to At a garage sale, all of the prices of the items sold were in the Problem Solving forum “The price of the radio was the 15th highest price So, there were 14 items that were more expensive than the radio. In other words, if we listed all of the prices in ascending order, we''d get something like: ........... radio, X, X, X, X, X, X, X, X, X, X, X, X, X, X The price of the radio ...” September 4, 2018 Brent@GMATPrepNow posted a reply to The average television prime-time advertising unit of 30 in the Problem Solving forum “We can also quickly solve this question by testing the answer choices.... Start with C (40%) 40% of$30,000 = $12,000 So, a 40% increase (from 1973 to 1977) =$30,000 + $12000 =$42,000 No good. We need to new amount to be $50,000 ELIMINATE C Since$42,000 is less than $50,000, we need a ...” September 4, 2018 Brent@GMATPrepNow posted a reply to Each of the following numbers has a remaider of 2 when in the Problem Solving forum “ASIDE: This is one of those questions that require us to check/test each answer choice. In these situations, always check the answer choices from E to A, because the correct answer is typically closer to the bottom than to the top. For more on this strategy, see my article: ...” September 4, 2018 Brent@GMATPrepNow posted a reply to At a certain hospital, 75% of the interns receive fewer than in the Problem Solving forum “I thought I''d point out that Mitch''s Double Matrix approach can be used for most questions featuring a population in which each member has two characteristics associated with it. Here, we have a population of interns, and the two characteristics are: - less than 6 hours sleep or 6 or more ...” September 4, 2018 Brent@GMATPrepNow posted a reply to DS_Arithmetic in the Data Sufficiency forum “Target question: What is the tenth digit in the decimal representation of a certain number? Jump straight to..... Statements 1 and 2 combined Statement 1 tells us that the number is less than 1/3 (aka 0.333333....) Statement 2 tells us that the number is greater than 1/4 (aka 0.25) ...” September 4, 2018 Brent@GMATPrepNow posted a reply to permutation/combination in the Problem Solving forum “This question is a little too ambiguous to be a true (official) GMAT question. Does order matter here? For example, is E driving, A in passenger seat, G in middle of back seat, and C in left side of back seat DIFFERENT FROM C driving, A in passenger seat, E in middle of back seat, and G in left ...” September 3, 2018 Brent@GMATPrepNow posted a reply to A store sold 6 bicycles with an average sale price of$1,000 in the Data Sufficiency forum
“Target question: What was the price of the most expensive bicycle? Given: The store sold 6 bicycles with an average sale price of $1,000. This means the SUM of the 6 bikes =$6000 (since $6000/6 bikes =$1000 average) Statement 1: The median price was $1,000. This statement doesn''t ...” September 3, 2018 Brent@GMATPrepNow posted a reply to Alex paid a$12 fee to receive a 10% discount off of the in the Problem Solving forum
“IMPORTANT: If Alex received a 10% discount, then Alex PAID 90% of the cost of the books If Victor received a 15% discount, then Victor PAID 85% of the cost of the books Start with a word equation Total amount Alex paid = Total amount Victor paid We get: $12 + 90% of b =$15 + 85% of b ...”
September 3, 2018
Brent@GMATPrepNow posted a reply to Paula and Sandy were among those people who sold raffle in the Data Sufficiency forum
“Target question: How many of the tickets did Paula sell? Given: Paula and Sandy sold a total of 100 of the tickets Let x = number of tickets that Paula sold This means 100-x = number of tickets that Sandy sold Statement 1: Sandy sold 2/3 as many of the raffle tickets as Paula did. We ...”
September 3, 2018
Brent@GMATPrepNow posted a reply to Six children — A, B, C, D, E, and F — are going to sit i in the Problem Solving forum
“Here are a few similar questions to practice with: - http://www.beatthegmat.com/permutation-t261691.html - http://www.beatthegmat.com/vowels-and-consonants-arrangement-t149946.html - http://www.beatthegmat.com/how-many-possible-orders-t277574.html Cheers, Brent”
September 3, 2018
Brent@GMATPrepNow posted a reply to integers in the Problem Solving forum
“Here''s one way to look at it. Write all of the numbers as 3-digit numbers. That is, 000, 001, 002, 003, .... 998, 999 NOTE: Yes, I have started at 000 and ended at 999, even though though the question asks us to look at the numbers from 1 to 1000. HOWEVER, notice that 000 and 1000 do not ...”
September 1, 2018
Brent@GMATPrepNow posted a reply to How many positive integers less than 2*10^4 are there in in the Problem Solving forum
“In other words, "How many positive integers less than 20,000 are there in which each digit is a prime number?" The prime digits are: 2, 3, 5 and 7 Notice that, using the digits 2, 3, 5 and 7, we cannot create a 5-digit number that''s less than 20,000 So, we must consider 4 possible ...”
September 1, 2018
Brent@GMATPrepNow posted a reply to Each baseball team in a league has a roster of players in in the Problem Solving forum
“There are 2 pitchers for every 3 fielders So, out of every 5 players, there are 2 pitchers. So, in ONE 25-player team, there are 10 pitchers (and 15 fielders) So, if there are 12 teams, and there are 10 pitchers and 15 fielders per team, then... TOTAL number of pitchers = (12)(10 ) TOTAL ...”
September 1, 2018
Brent@GMATPrepNow posted a reply to Which of the following are/is prime? in the Problem Solving forum
“I. 143 143 = (11)(13) Since 143 is NOT prime, we can ELIMINATE C, D and E II. 147 Notice that 147 = 140 + 7 Since 140 is divisible by 7, and 7 is divisible by 7, we know that 147 is divisible by 7. Since 147 is NOT prime, we can ELIMINATE A So, the answer (by the process of elimination) ...”
September 1, 2018
Brent@GMATPrepNow posted a reply to A certain library assesses fines for overdue books as in the Problem Solving forum
“1st day - $0.10 2nd day -$0.20 or $0.40 (double or add$0.30) $0.20 is the lesser amount 3rd day -$0.40 or $0.50 (double or add$0.30) $0.40 is the lesser amount 4th day -$0.80 or $0.70 (double or add$0.30) $0.70 is the lesser amount The correct answer is B Cheers, Brent” August 31, 2018 Brent@GMATPrepNow posted a reply to The Hazelton coal-processing plant is a major employer in in the Critical Reasoning forum “PREMISE: Coal plant will be shut down it it doesn''t upgrade PREMISE: Expensive upgrade will force company to close, UNLESS it receives tax break PREMISE: To PREVENT increase in local unemployment, government may grant tax break IMPORTANT: the government''s goal is to PREVENT an increase in ...” August 30, 2018 Brent@GMATPrepNow posted a reply to Angela has 15 pairs of matched socks. If she loses 7 in the Problem Solving forum “We can also systematically eliminate 4 of the 5 answer choices. Let''s say the 15 PAIRS of socks are as follows: AA, BB, CC, DD, EE, FF, GG, HH, II, JJ, KK, LL, MM, NN, OO Let''s first see what happens if we "lose" 7 unmatched socks. Say, we lose, A, B, C, D, E, F, G We get: A, B, ...” August 30, 2018 Brent@GMATPrepNow posted a reply to What is the range of 10 numbers? in the Data Sufficiency forum “Target question: What is the range of 10 numbers? Statement 1: The average (arithmetic mean) of the 10 numbers is 10 Let''s TEST some values. There are several sets of numbers that satisfy statement 1. Here are two: Case a: the numbers are {10, 10, 10, 10, 10, 10, 10, 10, 10, 10}. In this ...” August 30, 2018 Brent@GMATPrepNow posted a reply to A jar contains 16 red balls and 8 white balls. If 3 balls ar in the Problem Solving forum “There are 24 balls in the jar (before any are removed) P(all 3 balls are white) = P(1st ball is white AND 2nd ball is white AND 3rd ball is white) = P(1st ball is white) x P(2nd ball is white) x P(3rd ball is white) = 8/24 x 7/23 x 6/22 = 1/3 x 7/23 x 3/11 = 7/253 ASIDE: rather than ...” August 30, 2018 Brent@GMATPrepNow posted a reply to Pumping alone at their respective constant rates, one inlet in the Problem Solving forum “Let''s assign a nice value to the volume of the tank. We want a volume that works well with the given information (1/2, 2/3, 3 hours and 6 hours). So, let''s say the tank has a total volume of 18 gallons One inlet pipe fills an empty tank to 1/2 of capacity in 3 hours 1/2 the tank is 9 ...” August 30, 2018 Brent@GMATPrepNow posted a reply to At a constant rate of flow, it take 20 minutes to fill a in the Problem Solving forum “Let''s assign a nice value to the volume of the pool. We want a volume that works well with the given information (20 minutes and 30 minutes). So, let''s say the pool has a total volume of 60 gallons It takes 20 minutes to fill a swimming pool with a LARGE hose In other words, the LARGE hose ...” August 30, 2018 Brent@GMATPrepNow posted a reply to If 4 is one solution of the equation x^2 + 3x + k = 10, in the Problem Solving forum “Let''s first determine the value of k. Since x = 4 is a solution to the equation x² + 3x + k = 10, we know that x = 4 SATISFIES the equation. That is: 4² + 3(4) + k = 10 Evaluate to get: 16 + 12 + k = 10 Solve for k to get: k = -18 So, the ORIGINAL equation is x² + 3x + (-18) = 10 ...” August 30, 2018 Brent@GMATPrepNow posted a reply to In a certain summer school program, there are five periods in the Problem Solving forum “Take the Science, and Science Lab classes and "glue" them together to get the super class "Science-Science-Lab" This ensures that Science Lab immediately follows the Science class So, we now have only 4 classes: English, Math, History and Science-Science-Lab We can arrange ...” August 29, 2018 Brent@GMATPrepNow posted a reply to Is the measure of one of the interior angles of in the Data Sufficiency forum “Target question: Is the measure of one of the interior angles of quadrilateral ABCD equal to 60? Key concept: the 4 angles in a quadrilateral must add to 360 degrees Statement 1: Two of the interior angles of ABCD are right angles. Let''s test some possible cases. There are infinitely ...” August 28, 2018 Brent@GMATPrepNow posted a reply to Solution X, which is 50% alcohol, is combined with solution in the Problem Solving forum “When solving mixture questions, I find it useful to sketch the solutions with the ingredients SEPARATED: https://i.imgur.com/X6UPop8.png Since we want to determine the volume of solution Y needed, let''s... ...let y = volume (in liters) of solution Y needed This means 16 - y = volume (in ...” August 28, 2018 Brent@GMATPrepNow posted a reply to Is xy>0? in the Data Sufficiency forum “Target question: Is xy>0? Statement 1: x + y > 0 This statement doesn''t FEEL sufficient, so I''ll TEST some values. There are several values of x and y that satisfy statement 1. Here are two: Case a: x = 1 and y = 1. In this case, xy = (1)(1) = 1. So, the answer to the target ...” August 28, 2018 Brent@GMATPrepNow posted a reply to When traveling at a constant speed of 32 miles per hour, a in the Problem Solving forum “Let''s see what happens after ONE HOUR of traveling. In ONE hour, the boat will travel 32 miles and will use 24 gallons of fuel So, the fuel consumption rate is 32 miles per 24 gallons Or we can write: fuel consumption rate = 32/24 miles/gallon 32/24 = 4/3 So, the fuel consumption rate = ...” August 28, 2018 Brent@GMATPrepNow posted a reply to Exactly 8 years ago, Jim's son was twice as old as Jim's in the Problem Solving forum “Jim’s son is now 5 years older than his daughter Let D = the daughter''s age NOW So D + 5 = the son''s age NOW This also means that D - 8 = the daughter''s age EIGHT YEARS AGO This also means that D + 5 - 8 = the son''s age EIGHT YEARS AGO Or we can say, D - 3 = the son''s age EIGHT YEARS ...” August 28, 2018 Brent@GMATPrepNow posted a reply to What is the sum of all multiples of 3 between 1 and 200? in the Problem Solving forum “Useful formula: 1 + 2 + 3 + 4 + . . . n = (n)(n + 1)/2 We want to find the sum: 3 + 6 + 9 + 12 + . . . 198 Factor out the 3 to get: 3(1 + 2 + 3 + 4 + . . . 66) Apply formula to get: 3(66)(67)/2 Evaluate to get: 6633 Answer: C Cheers, Brent” August 28, 2018 Brent@GMATPrepNow posted a reply to What is the value of x? in the Data Sufficiency forum “Here''s another way to look at it..... (1) 310x + 562y = 909 We can think of this as the equation of a line. The x- and y-coordinates of all points on the line will satisfy the equation 310x + 562y = 909 Since there are infinitely many points on the line, there are infinitely many possible ...” August 27, 2018 Brent@GMATPrepNow posted a reply to George bought a large electronic item with a 15% off coupon, in the Problem Solving forum “George was SUPPOSED to receive a 15% discount, but he received a 30% discount. So, he should have returned 15% of the original cost. However, the manager asked for half that amount (i.e., 7.5% of the original cost) In other words, 7.5% of the original cost =$40.50 IMPORTANT: at this point, ...”
August 27, 2018
Brent@GMATPrepNow posted a reply to GMAT Prep Problem 3 in the Problem Solving forum
“Here''s the complete question: Let''s first determine the least possible integer. We''ll use the answer choices to help us along... A) Could the smallest value on the card be 3? Well, the next larger integer is 4, and 3 x 4 = 12, which is OUTSIDE the given range of 15 to 200 So, we ...”
August 27, 2018
Brent@GMATPrepNow posted a reply to GMAT Prep Problem 1 in the Problem Solving forum
“Here''s another algebraic approach. Let M = Alice''s monthly take home pay Let f = the fraction we''ll use to calculate monthly savings The means that fM = the amount of $Alice saves each month. And this means that her annual savings = 12fM Important: If f = the fraction used to ...” August 27, 2018 Brent@GMATPrepNow posted a reply to If m and n are integers greater than 1, is m^n>500? in the Data Sufficiency forum “Target question: Is m^n > 500? Given: m and n are integers greater than 1 Statement 1: n > 8 We''re told that m and n are integers greater than 1 So, the SMALLEST possible value of m is 2 And, if n > 8, the SMALLEST possible value of n is 9 When we plug in these SMALLEST ...” August 27, 2018 Brent@GMATPrepNow posted a reply to If x and y are positive integers and xy=36, what is the smal in the Problem Solving forum “Since there aren''t many PAIRS of integers that have a product of 36, we can simply list the possibilities: x = 1 and y = 36. Here, the SUM = 37 x = 2 and y = 18. Here, the SUM = 20 x = 3 and y = 12. Here, the SUM = 15 x = 4 and y = 9. Here, the SUM = 13 x = 6 and y = 6. Here, the SUM = 12 ...” August 27, 2018 Brent@GMATPrepNow posted a reply to For which of the following functions is f(a+b) = F(a) + f(b) in the Problem Solving forum “One approach is to plug in numbers. Let''s let a = 1 and b = 1 So, the question becomes, "Which of the following functions are such that f(1+1) = f(1) + f(1)?" In other words, for which function does f(2) = f(1) + f(1)? A) If f(x)=x², does f(2) = f(1) + f(1)? Plug in to get: 2² ...” August 27, 2018 Brent@GMATPrepNow posted a reply to If n = 10^10 and n^n = 10^d, what is the value of d? A. 10^ in the Problem Solving forum “A slightly different approach.... Given: n = 10^10 Also given: n^n = 10^d Replace n in the base with 10^10 to get: (10^10)^n = 10^d Apply Power of a Power rule on left side to get: 10^10n = 10^d So, we can conclude that 10n = d Now replace the remaining n with 10^10 to get: 10(10^10) = d ...” August 26, 2018 Brent@GMATPrepNow posted a reply to If it takes Jacob x hours to complete a project and it in the Problem Solving forum “For work questions, there are two useful rules: Rule #1: If a person can complete an entire job in k hours, then in one hour, the person can complete 1/k of the job Example: If it takes Sue 5 hours to complete a job, then in one hour, she can complete 1/5 of the job. In other words, her work ...” August 25, 2018 Brent@GMATPrepNow posted a reply to Each of the following numbers has a remaider of 2 when in the Problem Solving forum “A. 2 divided by 11 equals 0 with remainder 2. ELIMINATE B. 13 divided by 11 equals 1 with remainder 2. ELIMINATE C. 24 divided by 11 equals 2 with remainder 2. ELIMINATE D. 57 divided by 11 equals 5 with remainder 2. ELIMINATE By the process of elimination, the correct answer MUST be E Let''s ...” August 25, 2018 Brent@GMATPrepNow posted a reply to If each of the two digits X and Y is distinct in the Data Sufficiency forum “Target question: Is the two-digit integer xy prime? Given: Each of the two digits x and y is distinct Statement 1: Each of the digits x and y is the sum of 2 distinct single digit prime numbers. Let''s TEST some values. There are several values of x and y that satisfy statement 1. Here ...” August 25, 2018 Brent@GMATPrepNow posted a reply to Is w less than y? in the Data Sufficiency forum “Target question: Is w less than y? Statement 1: 1.3 < w < 1.3101 Since we have no information about y, there''s no way to determine whether w is less than y Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT Statement 2: 1.3033 < y Since we ...” August 25, 2018 Brent@GMATPrepNow posted a reply to What is the sum of all of the integers in the chart above? in the Problem Solving forum “Always check the answer choices BEFORE solving the question!! Since the answer choices are nicely spread apart, we can be quite aggressive in our estimation Let''s add the 5 numbers in each COLUMN COLUMN 1: Sum ≈500 COLUMN 2: Sum ≈-1000 COLUMN 3: Sum ≈1500 COLUMN 4: Sum ≈-2000 ...” August 25, 2018 Brent@GMATPrepNow posted a reply to After receiving a 25% discount, Amanda pays$240 for a TV. in the Problem Solving forum
“Another approach is to TEST THE ANSWER CHOICES.... If Amanda received a 25% discount, then she paid 75% of the original price. In other words, she paid 3/4 of the original price. We''re told she paid $240, so we''ll check the answer choices to see which one yields an output of$240 when we ...”
August 25, 2018
Brent@GMATPrepNow posted a reply to After receiving a 25% discount, Amanda pays $240 for a TV. in the Problem Solving forum “Let x = the original price (BEFORE the discount) If Amanda received a 25% discount, then she paid 75% of the original price. In other words, she paid 75% of x We''re told she paid$240, so we can write: 75% of x = $240 Or we can write: 0.75x = 240 ASIDE: One approach here is to divide ...” August 25, 2018 Brent@GMATPrepNow posted a reply to A gambler rolls three fair six-sided dice. What is the in the Problem Solving forum “Let''s first calculate P(same, same, different) P(same, same, different) = P(1st roll is ANY value AND 2nd roll matches 1st roll AND 3rd roll is different from first 2 rolls) = P(1st roll is ANY value) x P(2nd roll matches 1st roll) x P(3rd roll is different from first 2 rolls) = 6/6 x 1/6 x 5/6 ...” August 25, 2018 Brent@GMATPrepNow posted a reply to Michael drives x miles due north at arrives at Point A. He in the Problem Solving forum “At the risk of being that guy, I believe the answer is E. Here''s why: We already know that, if we start at a place on the equator and walk 40,000 km (the approximate circumference of Earth) due east, we will end up at the same place we started. If we start at a place further north (say Los ...” August 25, 2018 Brent@GMATPrepNow posted a reply to f 412*378 = A, then which of the following is equal to 412*3 in the Problem Solving forum “Given: (412)(378) = A We must find the value of (412)(379). (412)(379) = (412)(378 + 1) = (412)(378) + (1)(412) = A + 412 Answer: D Cheers, Brent” August 24, 2018 Brent@GMATPrepNow posted a reply to If the sales tax on a$12.00 purchase is $0.66, what is the in the Problem Solving forum “We can also solve this question using equivalent ratios We''re comparing sales tax to retail price We get: sales tax/retail price =$0.66/$12.00 What is the sales tax on a$20.00 purchase? Let x = the sales tax We can write: $0.66/$12.00 = x/$20.00 Cross multiply to get: (0.66)(20) = ...” August 24, 2018 Brent@GMATPrepNow posted a reply to At a bowling alley, Neil can win a free pair of bowling in the Problem Solving forum “At a bowling alley, Neil can win a free pair of bowling shoes if he averages a score of at least 200 over 8 games. If the average of the 8 games = 200, then we can write: (sum of all 8 scores)/8 = 200 Multiply both sides by 8 to get: sum of all 8 scores = 1600 If his scores in his first seven ...” August 24, 2018 Brent@GMATPrepNow posted a reply to Last month, a florist gave 7 percent of her sales revenue to in the Problem Solving forum “Choose a "nice" number for the sales revenue Let$100 = LAST MONTH''s revenue So, $120 = THIS MONTH''s revenue (since sales were up 20 percent from last month) LAST month, a florist gave 7 percent of her sales revenue to her employees in bonuses So, bonuses = 7% of$100 = $7 ...” August 24, 2018 Brent@GMATPrepNow posted a reply to A librarian has a set of ten books, including four different in the Problem Solving forum “Let''s first "glue" the 4 Lincoln books together to create one SUPER BOOK (this will ensure that the 4 books remain together) We now have 7 books: 6 regular books and 1 super book We can arrange these 7 books in 7! ways. KEY: For each of the 7! arrangements, we can take the 4 Lincoln ...” August 24, 2018 Brent@GMATPrepNow posted a reply to If n is a positive integer, which of the following can’t b in the Problem Solving forum “KEY CONCEPTS: #1) If n is an integer, then n and n+1 are consecutive integers #2)If n and n+1 are consecutive integers, then one value is ODD and the other value is EVEN #3)ODD^4 = (ODD)(ODD)(ODD)(ODD) = ODD #4)EVEN^4 = (EVEN)(EVEN)(EVEN)(EVEN) = EVEN #5)(odd)-(odd) = even #6)(odd)-(even) = ...” August 24, 2018 Brent@GMATPrepNow posted a reply to The average (arithmetic mean) of the five numbers in a data in the Problem Solving forum “Let a, b, c, d and e be the five numbers in the set. The average (arithmetic mean) of the five numbers in a data set is 72. So, (a + b + c + d + e)/5 = 72 Multiply both sides of the equation by 5 to get: a + b + c + d + e = 360 The average (arithmetic mean) of the first three numbers is ...” August 24, 2018 Brent@GMATPrepNow posted a reply to What is the length of the sides of a given cube? in the Data Sufficiency forum “IMPORTANT: For geometry Data Sufficiency questions, we are typically checking to see whether the statements "lock" a particular angle, length, or shape into having just one possible measurement. This concept is discussed in much greater detail in the following video: Target question: What ...” August 23, 2018 Brent@GMATPrepNow posted a reply to A whole number greater than 1 has remainders of 1 when it is in the Problem Solving forum “Let N = the number in question. If N divided by 2 leaves a remainder of 1, then N is 1 greater than some multiple of 2. This means that N - 1 must be a multiple of 2. Likewise, if N divided by 3 leaves a remainder of 1, then N is 1 greater than some multiple of 3. This means that N - 1 ...” August 23, 2018 Brent@GMATPrepNow posted a reply to If n is the smallest integer such that 432 times n is the in the Problem Solving forum “IMPORTANT CONCEPT: The prime factorization of a perfect square (the square of an integer) will have an even number of each prime For example: 400 is a perfect square. 400 = 2x2x2x2x5x5. Here, we have four 2''s and two 5''s This should make sense, because the even numbers allow us to split the ...” August 23, 2018 Brent@GMATPrepNow posted a reply to United Telephone charges a base rate of$10.00 for service, in the Problem Solving forum
“Let x = the number of minutes used United Telephone charge = $10.00 +$0.25x Atlantic Call charge = $12.00 +$0.20x For what number of minutes would the bills for each telephone company be the same? In other words, for what value of x does $10.00 +$0.25x EQUAL $12.00 +$0.20x? Let''s ...”
August 23, 2018
Brent@GMATPrepNow posted a reply to Alice, Bob, Cindy, Dave and Eddie joined a three-person-a-si in the Problem Solving forum
“When the answer choices are relatively small (as they are here), we should also consider just [size=150]listing the possible outcomes[/size]. They are: ABC ABD ABE ACD ACE ADE BCD BCE BDE CDE Answer: E Cheers, Brent”
August 22, 2018
Brent@GMATPrepNow posted a reply to If x and y are integers, is x^3+3x-y an even number? in the Data Sufficiency forum
“-----ASIDE------------------------- Some important rules: 1. ODD +/- ODD = EVEN 2. ODD +/- EVEN = ODD 3. EVEN +/- EVEN = EVEN 4. (ODD)(ODD) = ODD 5. (ODD)(EVEN) = EVEN 6. (EVEN)(EVEN) = EVEN ------------------------------------- Target question: Is x³ + 3x - y an even number? ...”
August 22, 2018
Brent@GMATPrepNow posted a reply to Alice, Bob, Cindy, Dave and Eddie joined a three-person-a-si in the Problem Solving forum
“The order in which we select the 3 starters does not matter. For example, selecting Alice then Cindy and then Dave to be the starters is the SAME as selecting Cindy then Dave and then Alice to be the starters. Since order does not matter, we can use COMBINATIONS We can select 3 players from 5 ...”
August 22, 2018
Brent@GMATPrepNow posted a reply to What is the decimal equivalent of (1/5)^5? in the Problem Solving forum
“Another approach: Given: (1/5)^5 Rewrite as: 1/(5^5) Create equivalent fraction by multiplying top and bottom by 2^5 to get: 2^5/(2^5)(5^5) Simplify: 32/10^5 Simplify: 32/100,000 STOP. So, the decimal equivalent will have 32 in. Check the answer choices.....only A works. Answer: ...”
August 22, 2018
Brent@GMATPrepNow posted a reply to What is the decimal equivalent of (1/5)^5? in the Problem Solving forum
“Here''s one approach: (1/5)⁵ = (2/10)⁵ = (2⁵)/(10⁵) = 32/100,000 = 0.00032 = A Cheers, Brent”
August 21, 2018
Brent@GMATPrepNow posted a reply to In the biology lab of "Jefferson" High School ther in the Problem Solving forum
“Germs per dish = (total number of germs)/(total number of dishes) total number of germs = 0.037 x 10^5 = 3700 total number of dishes = 74000 x 10^(-3) = 74 So, Germs per dish = (3700)/(74) = (37)(100)/(37)(2) = 100/2 = 50 Answer: E Cheers, Brent”
August 21, 2018
Brent@GMATPrepNow posted a reply to One machine, working at a constant rate, can fill a certain in the Problem Solving forum
“Let''s assign a "nice" value to the entire job (a value that works well with the given information) Let''s say the machine is making widgets and an order = 8 widgets. One machine, working at a constant rate, can fill a production order in 8 hours. In other words, ONE machine can ...”
August 21, 2018
Brent@GMATPrepNow posted a reply to In the xy-coordinate plane, which of the following points in the Problem Solving forum
“APPROACH #2: Rewrite the equation in slope y-intercept form y = mx + b, where m is the slope of the line and b is the line''s y-intercept Take: kx + 3y = 6 Subtract kx from both sides: 3y = 6 - kx Divide both sides by 3 to get: y = 2 - kx/3 Rewrite as: y = (k/3)x + 2 So, the slope of the ...”
August 20, 2018
Brent@GMATPrepNow posted a reply to In the xy-coordinate plane, which of the following points in the Problem Solving forum
“APPROACH #1: The key here is "for every possible value of k" So, let''s assign a value of k and see what happens. How about k = 0? When k = 0, the equation becomes: (0)x + 3y = 6 Simplify: 3y = 6 Solve: y = 2 So, in this case, the y-coordinate must be 2! Check the answer ...”
August 20, 2018
Brent@GMATPrepNow posted a reply to The median of a data set is x and its maximum is 40. The ran in the Problem Solving forum
“Your suggestion that range = 2(maximum value - median) is not always true In fact, the only time the range = 2(maximum value - median) is when the median is the average of the minimum and maximum value. For example, in the set {1, 9, 17}, the range = 17 - 1 = 16, which is equal to 2(maximum value ...”
August 20, 2018