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 ...”
Yesterday
GMATGuruNY posted a reply to In an office that employs 120 people, m% of the employees in the Data Sufficiency forum
“Use a DOUBLE-MATRIX to organize the data. Statements combined: Case 1: m=25% and c=25% Total number of males = (25/100)(120) = 30. Total number of custodial employees = (25/100)(120) = 30. The following matrix is yielded: https://i.postimg.cc/H88Lq5zN/matrix_custodial_1.png In this case, ...”
Yesterday
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
GMATGuruNY posted a reply to In these difficult economic times, those who have---Veriats in the Sentence Correction forum
“The default referent for a subject pronoun is the subject of the preceding INDEPENDENT CLAUSE. A: Those who have public pensions are being pursued strongly by pension advance companies that operate without much oversight from banking regulators, but they are now drawing scrutiny. Here, the default ...”
September 21, 2018
GMATGuruNY posted a reply to GMATPREP Question - what is the subject in the Sentence Correction forum
“This interpretation is not valid. The comparative in blue is clearly an ADJECTIVE describing a city.. Since as big as refers not to China but to A CITY. no comparison between China and Singapore is implied. The sentence unambiguously compares A CITY to Singapore, as discussed below. ...”
September 21, 2018
GMATGuruNY posted a reply to If m > 0, y > 0, and x is m percent of 2y, then, in te in the Problem Solving forum
“Let y=100, implying that 2y = 200. Let m=100. x is m percent of 2y. Since m=100 and 2y=200, x = 100% of 200 = 200. m is what percent of x? m/x = 100/200 = 1/2 = 50%. This is our target. Now plug y=100 into the answers to see which yields the target value of 50. Only E works: 5000/y = ...”
September 21, 2018
GMATGuruNY posted a reply to If 7 < m < 11 and −2 < n < 5, then which of th in the Problem Solving forum
“To determine the lower limit and the upper limit of mn, calculate mn using every combination of endpoints (7 and 11 for m, -2 and 5 for n): mn = (7)(-2) = -14. mn = (7)(5) = 35. mn = (11)(-2) = -22. mn = (11)(5) = 55. The LOWER limit is the LEAST of the results above: -22. The UPPER ...”
September 21, 2018
GMATGuruNY posted a reply to The square ACEG shown below has an area of 36 units squared. in the Problem Solving forum
“Almost no math is needed here. Answer choice A implies the following: BCD is a 45-45-90 triangle in which each leg has a length of 1. DEF is a 45-45-90 triangle in which each leg has a length of 5. Answer choice E implies the following: BCD is a 45-45-90 triangle in which each leg has a ...”
September 20, 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
GMATGuruNY posted a reply to If Albert can travel 200 miles in 4 hours, how many hours in the Problem Solving forum
“Since Albert travels 200 miles in 4 hours, his rate = 200/4 = 50 mph. When the correct answer is divided into 350 miles, the resulting rate must be 50 mph. Only C works: 350/7 = 50. The correct answer is C.”
September 20, 2018
beatthegmat posted a reply to 2019 GMAC Official Guide applicable for 60-Day Study Guide? in the The 60-Day GMAT Study Guide forum
“Hi! We have all of the OG questions libraries available here: https://www.beatthegmat.com/official-guide-question-library-t296753.html. Specifically, you can find the OG 2019 question library here: https://www.beatthegmat.com/mba/official-guide-2019-library I hope this helps!”
September 20, 2018
GMATGuruNY posted a reply to In four years, Andy will be twice as old as Betsy. How old in the Data Sufficiency forum
“In four years, Andy will be twice as old as Betsy. Since Andy''s age in 4 years is twice Betsy''s age in 4 years, we get: A+4 = 2(B+4) A+4 = 2B+8 A-2B = 4. Statement 1: Since Andy''s age 4 years ago is twice Betsy''s current age, we get: A-4 = 2B A-2B = 4. Same equation as given in the ...”
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
GMATGuruNY posted a reply to How many multiples of 33 lie between 101 and 1,000, inclusiv in the Problem Solving forum
“Since 1000 - 101 ≈ 900 -- and the answer choices are a bit spread out -- we can count the multiples of 33 simply by dividing 33 into 900: 900/33 = 300/11 = a bit more than 27. Thus, there are 27 multiples of 33 between 101 and 1000. The correct answer is B.”
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
GMATGuruNY posted a reply to Comparison - GMAT paper test in the Sentence Correction forum
“OA: A neutron star, as small as 12 miles in diameter but containing half as much matter as the Sun, has a gravitational force at its surface about 67 billion times greater than that on Earth. The green portion conveys the following meaning: The words in brackets are omitted so that the green ...”
September 19, 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
GMATGuruNY posted a reply to Rasheed bought two kinds of candy bars, chocolate and toffee in the Data Sufficiency forum
“I believe that the problem has been transcribed incorrectly. Statement 1 should indicate that Rasheed bought not 2 fewer packages but only 1 fewer package, as shown in the following screen shot: https://i.postimg.cc/t7bcm77Z/rasheed_Gprep-ds-2.jpg If we know the number of chocolate BARS that ...”
September 19, 2018
GMATGuruNY posted a reply to √3-2|+|3-√2|+|5+√3|+|1-√2|=? in the Problem Solving forum
“|a-b| = the distance between a and b. |a+b| = |a-(-b| = the distance between a and -b. |√3-2| + |3-√2| + |5+√3| + |1-√2| = |5+√3| + |√3-2| + |1-√2| + |3-√2| = |√3+5| + |√3-2| + |1-√2| + |3-√2| = |√3-(-5)| + |√3-2| + |1-√2| + |3-√2| The red terms ...”
September 19, 2018
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September 19, 2018
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September 19, 2018
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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
GMATGuruNY posted a reply to On the number line shown, the distance between 0 and a, a in the Problem Solving forum
“In the number line shown, the distance between 0 and a, a and b, and a and c is in the ratio of 1:2:3. To determine the ratio of a to b to c, TEST AN EASY CASE. Let a=1. Since a is ONE PLACE to the right of 0, b must be TWO PLACES to the right of a (implying that b=3), while c must be THREE ...”
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
GMATGuruNY posted a reply to If 12 men and 16 women can do a piece of work in 5 days and in the Problem Solving forum
“Let M = the rate for each man and W = the rate for each woman. The TIME RATIO for 12 men and 16 women to 13 men and 24 women is 5 days to 4 days. Since time and rate are RECIPROCALS, the RATE RATIO for 12M+16W and 13M+24W is equal to the reciprocal of the time ratio: (12M+16W)/(13M+24W) = ...”
September 18, 2018
GMATGuruNY posted a reply to A certain investment grows at an annual interest rate of 8%, in the Problem Solving forum
“When a value increases repeatedly by r%: Final amount = Original amount * (1 + r/100)^number of changes. Let original amount = 1. Since the original amount increases by a factor of 16: Final amount = 16. Since the investment increases by 2% every quarter: r = 2. Since x = the number of ...”
September 18, 2018
GMATGuruNY posted a reply to Grandmother's Punch hangover cure is a mix of two in the Problem Solving forum
“We can PLUG IN THE ANSWERS, which represent the amount of cider. When the correct answer is plugged in, the amount of alcohol in the 750 ml bottle = 87 ml. Since the alcohol percentage in the cider = 5% = 1/20, the correct answer is almost certain to be a multiple of 20. Of the five answer ...”
September 17, 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
GMATGuruNY posted a reply to A tank has 5 inlet pipes. Three pipes are narrow and two are in the Problem Solving forum
“Let the rate of each wide pipe = 2 liters per hour. Combined rate for 2 wide pipes = 2*2 = 4 liters per hour. Since each narrow pipe works at 1/2 the rate of each wide pipe, the rate of each narrow pipe = (1/2)(2) = 1 liter per hour. Combined rate for 3 narrow pipes and 2 wide pipes = (3*1) + ...”
September 16, 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
GMATGuruNY posted a reply to Gunther, the pizza delivery boy, went out from the store in the Problem Solving forum
“Average = sum/quantity. In this case: Average speed = (sum of the minutes spent at each speed)/(total number of minutes). Total time spent at 15mph = 30 minutes. Total time spent delivering pizzas at 0mph = 30 minutes. Total time spent at 30mph = 15 minutes. Average speed = (15*30 + 0*30 + ...”
September 15, 2018
GMATGuruNY posted a reply to A basket contains 5 apples, of which 1 is spoiled and the in the Problem Solving forum
“P(spoiled apple is selected) = 1 - P(spoiled apple is NOT selected). P(1st apple is not spoiled) = 4/5. (Of the 5 apples, 4 are not spoiled). P(2nd apple is not spoiled) = 3/4. (Of the 4 remaining apples, 3 are not spoiled). Since we want both events to happen, we multiply the fractions: ...”
September 15, 2018
GMATGuruNY posted a reply to Point P is the point of the circle x^2 + y^2 -2x -4y = 4 wit in the Problem Solving forum
“(x-h)² + (y-k)² = r² is a circle with a center at (h, k) and a radius of r. x² + y² - 2x - 4y = 4 x² - 2x + y² - 4y = 4 x² - 2x + 1 + y² - 4y + 4 = 4 + 1 + 4 (x-1)² + (y-2)² = 9 (x-1)² + (y-2)² = 3³ The equation above constitutes a circle with a center at (1, 2) and a ...”
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
“Even if the zebra''s speed is the same in both cases, we can''t conclude anything about the distances, since we aren''t told anything about the direction the zebra is traveling. It may even be the case that the zebra is traveling in circles :-) Cheers, Brent”
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
GMATGuruNY posted a reply to At what speed was Erik running when he was at the halfway in the Data Sufficiency forum
“Statements combined: Each statement conveys the same information: that the average speed for the whole trip was 5 miles per hour. The AVERAGE speed for the whole trip does not constrain the speed AT THE HALWAY POINT. At the halfway point, the speed could be ANY NONNEGATIVE VALUE. Thus, the ...”
September 13, 2018
GMATGuruNY posted a reply to (1^2+2^2+3^3+…+20^2) / (1+2+3+ …+20)=? in the Problem Solving forum
“The answer choices represent the ratio between the numerator and the denominator of the given expression. Option A implies that the numerator is about 14 times the denominator Option B implies that the numerator is less than 7 times the denominator. Option C implies that the numerator is 41 times ...”
September 13, 2018
GMATGuruNY posted a reply to (1^2+2^2+3^3+…+20^2) / (1+2+3+ …+20)=? in the Problem Solving forum
“Since the answer choices are very spread out, we can BALLPARK -- and we can be somewhat lax with our estimations. Numerator: If the 11 greatest terms were 10²=100, the sum of the 11 greatest terms = 11*100 = 1100. If the 11 greatest terms were 20²=400, the sum of the 11 greatest terms = ...”
September 13, 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
GMATGuruNY posted a reply to If the interior angles of a triangle are in the ratio 3 to in the Problem Solving forum
“The sum of the 3 angles of a triangle = 180. The sum of the parts of the ratio = 3+4+5 = 12. Since 180/12 = 15, the multiplier for the ratio is 15, implying that the largest angle = 5*15 = 75. The correct answer is D.”
September 12, 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
GMATGuruNY posted a reply to During a one day sale, a store sold each sweater of a in the Data Sufficiency forum
“Statement 1: Case 1: 1 sweater is sold for $270 Case 2: 3 sweaters are sold for $90 each Since the number of sweaters sold can be different values, INSUFFICIENT. Statement 2: Since the $30 markup is 1/2 the cost of each sweater, the cost of each sweater = 60. Thus, the selling price of ...”
September 12, 2018
GMATGuruNY posted a reply to Three boys are ages 4, 6 and 7 respectively. Three girls are in the Problem Solving forum
“Since only a few cases are possible, we can list them out: 4+6+5+8 = 23 4+6+5+9 = 24 4+6+8+9 = 27 4+7+5+8 = 24 4+7+5+9 = 25 4+7+8+9 = 28 6+7+5+8 = 26 6+7+5+9 = 27 6+7+8+9 = 30 Of the 9 cases above, the four in red are ODD, implying that the remaining five cases are EVEN. Since 5/9 of ...”
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
GMATGuruNY posted a reply to The perimeter of a rectangular garden is 360 ft. What is the in the Data Sufficiency forum
“The GRE is administered by ETS, which also used to administer the GMAT. The GRE Quantitative Guide states that any side of a triangle or parallelogram can be used as a base. The GMAT is likely to abide by this definition. But the terms length and long seem to connote a different meaning when ...”
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
GMATGuruNY posted a reply to The perimeter of a rectangular garden is 360 ft. What is the in the Data Sufficiency forum
“Definitions of length: Merriam-Webster: The LONGER OR LONGEST dimension of an object. American Heritage: The measurement of something along its GREATEST dimension.”
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
GMATGuruNY posted a reply to a family has 5 children, what is the probability that there in the Problem Solving forum
“The problem should make clear that P(boy) = P(girl) = 1/2: P(exactly n times) = P(one way) * total possible ways. Let B = boy and G = girl. P(one way): One way to get exactly 3 boys and 2 girls is BBBGG. P(BBBGG) = 1/2 * 1/2 * 1/2 * 1/2 * 1/2 = 1/32. Total possible ways: Any ...”
September 11, 2018
GMATGuruNY posted a reply to The sum of the ages of Doris and Fred is y years. If Doris in the Problem Solving forum
“Since Doris is 12 years older than Fred, let Fred = 2 and Doris = 2+12 = 14. y = sum of their ages = 2+14 = 16. Since Fred = 2 and y=16, Fred''s age y years from now = 2+16 = 18. This is our target. Now plug y=16 into the answers to see which yields the target value of 18. Only D works: 3y/2 - ...”
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
GMATGuruNY posted a reply to The rate of a certain chemical reaction is directly in the Problem Solving forum
“The trick is translate the chemical relationship into the following equation: R = A²/B Here''s why the equation above works: 1)The problem states that R is directly proportional to A². Directly proportional means that as one value increases, the other value also increases by a ...”
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
GMATGuruNY posted a reply to In a certain pond, 50 fish were caught, tagged, and returned in the Problem Solving forum
“Of the 50 fish caught in the second catch, 2 were tagged: 2/50 = 4/100 = 4%. Since the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond, the total number of tagged fish -- 50 -- must be equal to about 4% of the total number of fish in the pond: 50 = ...”
September 10, 2018
GMATGuruNY posted a reply to If 5^{m-2}2^{m+2} is an n-digit integer, where m is an inte in the Problem Solving forum
“Since m=2 will yield an integer value for the given expression and will make the math easier, ignore the condition that m>2 and let m=2. Plugging m=2 into 5^(m-2) * 2^(m+2), we get: 5⁰2⁴ = 1*16 = 16. Since the result is a 2-digit integer, n=2. The correct answer must work for n=m=2. Only ...”
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
GMATGuruNY posted a reply to Sam's car was fined when he gave Joe and Peter a ride, so in the Problem Solving forum
“Thanks for the heads up. I''ve revised my post accordingly.”
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
GMATGuruNY posted a reply to What is the probability of n(n+1)(n+2) being evenly divisibl in the Data Sufficiency forum
“Statement 1: Since n is an integer, n(n+1)(n+2) = the product of 3 consecutive integers. WRITE IT OUT and LOOK FOR A PATTERN. 1*2*3 2*3*4 3*4*5 4*5*6 5*6*7 6*7*8 7*8*9 8*9*10 9*10*11 10*11*12 11*12*13 12*13*14 13*14*15 14*15*16 15*16*17 16*17*18 Each of the products in red ...”
September 9, 2018
GMATGuruNY posted a reply to Twenty-four men can complete a work in sixteen days.Thirty in the Problem Solving forum
“Let the rate for each man = 1 widget per day, implying that the rate for 24 men = 24 widgets per day. Since 24 men complete the job in 16 days, the total amount of work = rt = 24*16 widgets. Since 32 women require 24 days, the rate for 32 women = w/t = (24*16)/24 = 16 widgets per day. Since ...”
September 9, 2018
GMATGuruNY posted a reply to Sam's car was fined when he gave Joe and Peter a ride, so in the Problem Solving forum
“Given that the answers choices are integers, I believe that the following reflects the problem''s intent: The three fractions in the prompt -- 1/4, 1/3 and 1/2 -- imply that the fine must be divisible by 4, 3 and 2. Smallest possible case: Total fine = 4*3*2 = 24. Since Sam paid $4 less ...”
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
GMATGuruNY posted a reply to GMATPREP Question - what is the subject in the Sentence Correction forum
“Option B for SC18 in the OG12: Plants are more efficient at acquiring carbon than fungi. Logical interpretation 1: Plants are more efficient at acquiring carbon than Logical interpretation 2: Plants are more efficient at acquiring carbon than fungi Since B allows for more than one logical ...”
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
GMATGuruNY posted a reply to The bear alarm at Grizzly's Peak ski resort sounds an in the Problem Solving forum
“The alarm sounds for 3 of EVERY 4 BEARS that actually appear, If 4 bears appear, then the number of alarms = 3. Since the alarm sounds only 3 times for 4 bears, 1 of these 4 bears is undetected. Since there are 10 false alarms for every 1 undetected bear, the number of false alarms = 10. Thus, ...”
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
GMATGuruNY posted a reply to If a mixture of ground meat consists of 2 pounds of veal in the Problem Solving forum
“The answer choices represent the price per pound: (total cost)/(total number of pounds). Since 7 pounds are purchased, the correct answer must have a denominator of 7. A, C and D lack denominators and thus can be eliminated. Since the denominator in B does not have to be 7, eliminate B. The ...”
September 7, 2018
GMATGuruNY posted a reply to How many hours did it take Dale to drive from A-town to B-to in the Data Sufficiency forum
“Statement 1: Time and rate have a RECIPROCAL relationship. 3 TIMES AS FAST implies 1/3 THE TIME. Thus, the 2 hours that would be spent traveling 3 times as fast must be equal to 1/3 the actual time: 2 = (1/3)t t = 6 hours. SUFFICIENT. Statement 2: Here, the time can be any nonnegative ...”
September 7, 2018
GMATGuruNY posted a reply to A palindrome is a number that reads the same forward and in the Problem Solving forum
“Number of options for the units digit = 5. (1, 3, 5, 7, or 9.) Number of options for the thousands digit = 1. (Must be the same as the units digit.) Number of options for the hundreds digit = 10. (Any of the digits 0-9.) Number of options for the tens digit = 1. (Must be the same as the hundreds ...”
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
GMATGuruNY posted a reply to Last year the price per share of Stock X increased by k in the Problem Solving forum
“Original ratio: Let the original price = 1 and the original earnings = 1. Resulting ratio: price/earnings = 1/1 = 1. New ratio: Let k=200 and m=100. Since the price increases by k=200%, the new price = 1 + (200/100)(1) = 3. Since the earnings increase by m=100%, the new earnings = ...”
September 6, 2018
GMATGuruNY posted a reply to What is the sum of roots of the equation x^2 – 40x + 399 = in the Problem Solving forum
“For any quadratic in the form x² + bx + c = 0: Sum of the roots = -b. Product of the roots = c. In the given quadratic, b = -40. Thus, the sum of the roots = -b = -(-40) = 40. The correct answer is D.”
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
GMATGuruNY posted a reply to If 3x + 2y = -2z, what is x? in the Data Sufficiency forum
“Prompt: 3x + 2y + 2z = 0 Statement 1: Multiplying by 2, we get: 2x - 2y - 2z = 20 Adding together 3x+2y+2z=0 and 2x-2y-2z=20, we get: (3x+2y+2z) + (2x-2y-2z) = 0 + 20 5x=20 x=4. SUFFICIENT. Statement 2: Multiplying by 2, we get: 2x + 2y + 2z = -4 Subtracting 2x+2y+2z = -4 from ...”
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
GMATGuruNY posted a reply to A and B can complete a task in 20 days. B and C can complete in the Problem Solving forum
“Alternate approach: Let the job = 240 units. Since A+B take 20 days to complete the 240-unit job, A+B = 240/20 = 12 units per day. Since B+C take 30 days to complete the 240-unit job, B+C = 240/30 = 8 units per day. Since A+C take 40 days to complete the 240-unit job, A+C = 240/40 = 6 units ...”
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
GMATGuruNY posted a reply to If r is a positive integer, n=r^3 and 4,14, and 27 are facto in the Problem Solving forum
“Since 4, 14 and 27 are all factors of n, the prime-factorization of n must include 2*2, 2*7 and 3*3*3. n = r³ implies that n is a perfect cube. The prime-factorization of a perfect cube must include at least 3 of each prime factor. Thus, the prime-factorization of n must include at least three ...”
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
GMATGuruNY posted a reply to If x and y are integers, what is the least possible positive in the Problem Solving forum
“Make a list of integer options for |21x| and |35y|: |21x| = 0, 21, 42, 63, 84, 105... |35y| = 0, 35, 70, 105... The smallest positive sum is yielded in the following cases: 21x = 42 and 35y = -35, with the result that 21x + 35y = 42 - 35 = 7 21x = -63 and 35y = 70, with the result that 21x + ...”
September 4, 2018
GMATGuruNY posted a reply to absolute value in the Data Sufficiency forum
“if a < y < z < b , is |y-a| less than |y-b| ? 1) |z-a| < |z-b| 2) |y-a| < |z-b| |a-b| = the distance between a and b. Since a < y < z < b, we get the following number line: a..........y..........z..........b Statement 1: |z-a| < |z-b| Since the distance ...”
September 4, 2018
beatthegmat posted a new topic called MBA or Specialized Master’s Degree: Which is Best for You? in the Research MBA Programs forum
“When you think business school, you probably think MBA. A Master’s of Business Administration has long been a coveted — and often essential — qualification for business professionals. In recent years, however, the tide has begun to quietly shift, with more business school students than ever ...”
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
GMATGuruNY posted a reply to Triathlete Dan runs along a 2-mile stretch of river and then in the Problem Solving forum
“When the same distance is traveled at two different speeds, the average speed will be the same for ANY DISTANCE. Thus, we can solve the problem above using a distance that is divisible by the two speeds. Let the distance in each direction = 30 miles. Time to run 30 miles at a rate of 10 miles per ...”
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
GMATGuruNY posted a reply to permutation/combination in the Problem Solving forum
“Mr. Smith shook hands with 3 times as many men as women. The phrase in blue implies that the number of men who shook hands with Mr. Smith is a MULTIPLE OF 3. Thus, the total number of men = (multiple of 3) + (Mr. Smith). In math terms: Number of men = 3a + 1, where a is a positive integer. ...”
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
GMATGuruNY posted a reply to GMATPREP Question - what is the subject in the Sentence Correction forum
“A comparison is questionable if it allows for more than one logical interpretation. Case 2 is not a logical interpretation of your revision of E. No reader will construe that what MANAGERS find is being compared to what A GRASPING finds. Since only Case 1 constitutes a logical interpretation, the ...”
September 4, 2018
GMATGuruNY posted a reply to At a certain hospital, 75% of the interns receive fewer than in the Problem Solving forum
“We can use a double-matrix: https://preview.ibb.co/iUwRPe/matrix_interns.png In the resulting matrix, total not tired = 19/100 = 19%. The correct answer is C.”
September 4, 2018
GMATGuruNY posted a reply to Points (x,y) in the rectangular coordinate plane in the Problem Solving forum
“Since the graph intercepts the x-axis to the left of the y-axis and has only one solution, its graph is as follows: y = (x-k)², where k<0. The equation above has an x-intercept at (k, 0), as shown in the figure above. The answer choices represent the sum of k (the x-intercept) and p (the ...”
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
GMATGuruNY posted a reply to Six children — A, B, C, D, E, and F — are going to sit i in the Problem Solving forum
“Alternate approach: Number of options for A = 6. (Any of the 6 chairs.) Number of options for B = 5. (Any of the 5 remaining chairs.) Number of options for C = 4. (Any of the 4 remaining chairs.) Number of options for D = 3. (Any of the 3 remaining chairs.) Number of options for E and F = 1. ...”
September 3, 2018
GMATGuruNY posted a reply to Is |xy|>x^2y^2 in the Data Sufficiency forum
“Looks good!”
September 2, 2018
GMATGuruNY posted a reply to 3 machines have a productivity ratio of 1 to 2 to 5. All 3 in the Problem Solving forum
“Let the rate for the fastest machine = 5 units per hour and the rate for the slowest machine = 1 unit per hour. Since the fastest machine works at a rate of 5 units per hour for all 9 hours, the work produced by the fastest machine = rt = 5*9 = 45 units. Since the slowest machine works at a rate ...”
September 2, 2018
GMATGuruNY posted a reply to Is x an integer? in the Data Sufficiency forum
“Statement 1: x/2 = 1, 2, 3, 4, 5... Multiplying every value by 2, we get: x = 2, 4, 6, 8, 10... In every case, x is an integer. SUFFICIENT. Statement 2: 2x = 1, 2, 3, 4, 5... Dividing every value by 2, we get: x = 1/2, 1, 3/2, 2, 5/2... If x=1/2, then x is not an integer. If x=1, then x ...”
September 2, 2018
GMATGuruNY posted a reply to integers in the Problem Solving forum
“If we use 0 as a placeholder -- so that 007 represents 7, 072 represents 72, etc. -- then we need to count the number of times that 7 will appear among the 3-digit integers from 000 to 999, inclusive. Total number of 3-digit integers from 000 to 999, inclusive = biggest - smallest + 1 = ...”
September 1, 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
GMATGuruNY posted a reply to If x^2/9 – 4/y^2 = 12, what is the value of x? in the Data Sufficiency forum
“x²/9 – 4/y² = 12 (x/3)² - (2/y)² = 12 The resulting equation is the DIFFERENCE OF TWO SQUARES: a² - b² = (a+b)(a-b). Thus, the equation can be rephrased as follows: (x/3 + 2/y)(x/3 - 2/y) = 12. Statement 1: Substituting x/3 + 2/y = 6 into (x/3 + 2/y)(x/3 - 2/y) = 12, we get: ...”
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
GMATGuruNY posted a reply to Agatha Christie´s Escalator in the Problem Solving forum
“Algebraic approach: Let P = Poirot''s rate, M = Marple''s rate, and E = the escalator''s rate. Since P travels 3 steps for every 2 steps that M travels: P/M = 3/2. Ratios can be MULTIPLIED: P/E * E/M = P/M . Since P/M = 3/2, we get: P/E * E/M = 3/2 Let x = the number of steps on ...”
August 30, 2018
GMATGuruNY posted a reply to Agatha Christie´s Escalator in the Problem Solving forum
“Let P = Poirot''s rate, M = Marple''s rate, and E = the escalator''s rate. Since P travels 3 steps for every 2 steps that M travels: P/M = 3/2. Ratios can be MULTIPLIED: P/E * E/M = P/M Since P/M = 3/2, we get: P/E * E/M = 3/2. We can PLUG IN THE ANSWERS, which represent the number of ...”
August 30, 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
GMATGuruNY posted a reply to If 4 is one solution of the equation x^2 + 3x + k = 10, in the Problem Solving forum
“Alternate approach: x² + 3x = 10-k x² + 3x = constant. Since x=4 and the correct answer choice are both roots, they must yield the same result when plugged into x² + 3x. Plugging x=4 into x² + 3x, we get: 4² + 3*4 = 28. If we test the answer choices, only x=-7 yields the same result ...”
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
GMATGuruNY posted a reply to A jar contains 16 red balls and 8 white balls. If 3 balls ar in the Problem Solving forum
“P(1st marble is white) = 8/24. (Of the 24 marbles, 8 are white.) P(2nd marble is white) = 7/23. (Of the 23 remaining marbles, 7 are white.) P(3rd marble is white) = 6/22. (Of the 22 remaining marbles, 6 are white.) To combine these probabilities, we multiply: 8/24 * 7/23 * 6/22 = 1/3 * 7/23 * ...”
August 30, 2018
GMATGuruNY posted a reply to In a certain summer school program, there are five periods in the Problem Solving forum
“Alternate approach: Since Science class must be followed immediately by Science lab, Science class cannot be taken during the last period. Thus: Number of options for Science class = 4. (Any of the first 4 periods.) Number of options for Science lab = 1. (Must be the period immediately after ...”
August 30, 2018
GMATGuruNY posted a reply to What is the value of j + k? in the Data Sufficiency forum
“Statement 1: Case 1: m=0, j=0, k=0 In this case, j+k = 0+0 = 0 Case 2: m=0, j=0, k=1 In this case, j+k = 0+1 = 1 Since j+k can be different values, INSUFFICIENT. Statement 2: Dividing both sides of the equation by 5, we get: j+k = 2. SUFFICIENT. The correct answer is B.”
August 30, 2018
GMATGuruNY posted a reply to Angela has 15 pairs of matched socks. If she loses 7 in the Problem Solving forum
“15 matched pairs = 30 socks. E: 12 If Angela has 12 matched pairs left -- for a total of 24 socks -- then the number of socks lost = 30-24 = 6. Not viable, since Angela must lose 7 socks. The correct answer is E.”
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
GMATGuruNY posted a reply to To fill a number of vacancies, an employer must hire 3 in the Problem Solving forum
“Number of ways to choose 3 programmers from 6 applicants = 6C3 = (6*5*4)/(3*2*1) = 20. Number of ways to choose 2 managers from 4 applicants = 4C2 = (4*3)/(2*1) = 6. To combine the options above, we multiply: 20*6 = 120. The correct answer is C.”
August 29, 2018
GMATGuruNY posted a reply to What is the units digit of (3^{101})(7^{103})? in the Problem Solving forum
“When an integer is raised to consecutive powers, the resulting units digits repeat in a CYCLE. 3¹⁰¹: 3¹ --> units digit of 3. 3² --> units digit of 9. (Since the product of the preceding units digit and 3 = 3*3 = 9.) 3³ --> units digit of 7. (Since the product of the ...”
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
GMATGuruNY posted a reply to It takes the high-speed train x hours to travel the z miles in the Problem Solving forum
“Plug in easy numbers for the two rates. Then plug in a distance that is a multiple of both the two individual rates and the COMBINED rate. Let the high speed rate = 3 miles per hour. Let the regular rate = 2 miles per hour. Combined rate for the trains = 2+3 = 5 miles per hour. Let z = ...”
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
GMATGuruNY posted a reply to The world wildlife fund has declared that global warming in the Sentence Correction forum
“a phenomenon that is caused by human beings. Here, the that-clause in green serves to modify a phenomenon. Question: What KIND of phenomenon? Answer: A phenomenon THAT IS CAUSED BY HUMAN BEINGS. Most scientists agree that the statement above is true. To convey this meaning, we insert most ...”
August 28, 2018
GMATGuruNY posted a reply to November is traditionally the strongest - OG 2018 in the Sentence Correction forum
“Incorrect: When compared with most sport utility vehicles, minivans get better gas mileage. Here, the usage of when compared is unwarranted and conveys a nonsensical meaning, implying that minivans GET better mileage at the same time as they are COMPARED. The following is sufficient to convey the ...”
August 28, 2018
GMATGuruNY posted a reply to How many different positive integers having six digits are in the Problem Solving forum
“How many ways can the letters BBBGG be arranged? Number of ways to arrange 5 elements = 5!. But when an arrangement includes IDENTICAL elements, we must divide by the number of ways each set of identical elements can be ARRANGED. The reason: When the identical elements swap positions, the ...”
August 28, 2018
GMATGuruNY posted a reply to A certain IT department of fewer than 15 people hires coders in the Data Sufficiency forum
“Let c = coders and s = system administrators. Statement 1: 55,000(c-2) + 45,000(s+2) = 535,000 55(c-2) + 45(s+2) = 535 11(c-2) + 9(s+2) = 107. Implication of the resulting equation: (multiple of 11) + (multiple of 9) = 107. (multiple of 9) = 107 - (multiple of 11). Subtract ...”
August 28, 2018
GMATGuruNY posted a reply to Justin, Max, and Paul each have a collection of marbles. in the Problem Solving forum
“Since Max has 30% more than Paul''s 80 marbles, Max = 80 + (3/10)(80) = 104. Since Justin has 50% fewer than Max''s 104 marbles, Justin = (1/2)(104) = 52. The correct answer is C.”
August 28, 2018
GMATGuruNY posted a reply to How many different positive integers having six digits are in the Problem Solving forum
“There are 6 positions in the integer. The two 4''s must occupy a pair of positions. From the 6 positions, the number of ways to choose a pair for the two 4''s = 6C2 = (6*5)/(2*1) = 15. The remaining 4 positions must be occupied by 3, 5, 7 or 8, 7 or 8. Number of options for the 3 = 4. (Any ...”
August 28, 2018
GMATGuruNY posted a reply to George bought a large electronic item with a 15% off coupon, in the Problem Solving forum
“We can PLUG IN THE ANSWERS, which represent the original price of the item. When the correct answer is plugged in, George reimburses the store $40.50. Since the coupon discount = 15% = 15/100 = 3/20, the original price of the item is almost certainly a multiple of 20. Of the 5 answer choices, ...”
August 27, 2018
GMATGuruNY posted a reply to Exactly 8 years ago, Jim's son was twice as old as Jim's in the Problem Solving forum
“We can PLUG IN THE ANSWERS, which represent the daughter''s current age. When the correct answer is plugged in, the nd the dau B: 10, implying that the daughter''s age 8 years ago = 10-8 = 2 Since the son 8 years ago was twice as old as the daughter, the son''s age 8 years ago = 2*2 = 4, ...”
August 27, 2018
GMATGuruNY posted a reply to If m and r are two numbers on a number line, what is the in the Data Sufficiency forum
“Translate the words into math. The DISTANCE between x and 0 is |x|. HALFWAY between two numbers is the AVERAGE of the two numbers. Statement 1: The distance between r and 0 is 3 times the distance between m and 0. |r| = 3|m| r = 3m or r=-3m. No way to solve for r. INSUFFICIENT. ...”
August 27, 2018
GMATGuruNY posted a reply to If a, b, and c are positive integers, what is the remainder in the Data Sufficiency forum
“Clearly, neither statement is sufficient on its own. Statements combined: The statements indicate that a and b are CONSECUTIVE PERFECT CUBES. Make a list of perfect cubes: 1, 8, 27, 64, 125... Calculating the difference between one perfect cube and the next, we get: 8-1 = 7 27-8 = 19 ...”
August 27, 2018
GMATGuruNY posted a reply to GMAT Prep Problem 1 in the Problem Solving forum
“Let the amount saved each month = $1. Total saved for the entire year = 12*1 = $12. Since the total saved for the entire year -- $12 -- is 3 times the total not saved each month, the total not saved each month = 12/3 = $4. Thus, the total monthly pay = (total saved each month) + (total not saved ...”
August 27, 2018
GMATGuruNY posted a reply to GMAT Prep Problem 3 in the Problem Solving forum
“The prompt requires the following: (greatest integer)(next largest integer) < 200. The answer choices imply that the greatest integer must be 13, 14, 15, or 20 15² = 225 and 20² = 400. Implication: (15)(next largest integer) and (20)(next largest integer) will each yield a product greater ...”
August 27, 2018
GMATGuruNY posted a reply to Solution X, which is 50% alcohol, is combined with solution in the Problem Solving forum
“We can PLUG IN THE ANSWERS, which represent the amount of Y. Since the percentage for the mixture (35%) is closer to Y''s percentage (30%) than to X''s percentage (50%), Y must constitute MORE THAN 1/2 of the 16-liter mixture. Thus, the amount of Y must be equal to more than 8 liters. Eliminate ...”
August 27, 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
GMATGuruNY posted a reply to Each of the cucumbers in 100 pounds is composed of 99% water in the Problem Solving forum
“Since the cucumbers are 99% water, the 100 pounds of cucumbers are composed of 99 pounds of water and 1 POUND OF OTHER STUFF. After evaporation makes the cucumbers 98% water, the 1 POUND OF OTHER STUFF must constitute 2% of the new total: 1 = (2/100)x x = 100/2 = 50. The correct answer ...”
August 26, 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
GMATGuruNY posted a reply to Of the 9,000 people who voted in a recent election, how many in the Data Sufficiency forum
“Statement 1: (women for X) : (women against X) = 2:1. Of every 3 women voters, 2 voted for X, while 1 voted against X. In other words, 2/3 of women voters voted for X. No way to determine the NUMBER of women who voted for X. INSUFFICIENT. Statement 2: No info about women voters. ...”
August 26, 2018
GMATGuruNY posted a reply to The sum of positive integers x and y is 77, what is the in the Data Sufficiency forum
“Statement 1: Substituting x=y+1 into x+y = 77, we get: (y+1) + y = 77 2y = 76 y = 38, implying that x = 38+1 = 39. Thus, xy = 39*38. SUFFICIENT. Statement 2: For x and y to have the same tens digit and a sum of 77, they must be equal to the pair of values yielded by Statement 1: 38 and ...”
August 26, 2018
GMATGuruNY 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
“Substituting n= 10¹⁰ into n^n = 10^d, we get: (10¹⁰ )^(10¹⁰)= 10^d When an exponent is raised to a power, we MULTIPLY the exponents. Multiplying the exponents in blue, we get: 10^(10*10¹⁰) = 10^d 10^(10¹¹) = 10^d Since each side has the same base, the exponent in blue must be ...”
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
GMATGuruNY posted a reply to How many five-digit numbers can be formed from the digits in the Problem Solving forum
“For the 5-digit integer to be a multiple of 4, the last two digits must form a multiple of 4. Options: 04, 12, 20, 24, 32, 40, 52. Case 1: Last 2 digits include 0 Number options for the last 2 digits = 3. (04, 20 or 40.) Number of options for the ten-thousands place = 4. (Any of the 4 ...”
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
GMATGuruNY posted a reply to Michael drives x miles due north at arrives at Point A. He in the Problem Solving forum
“In deference to Brent''s concerns, the problem should read as follows: x miles north, y miles east, and z miles in a straight line back to x constitute a right triangle with legs x and y and hypotenuse z. The only right triangle in which all 3 sides are integers and the shortest leg is 5 is ...”
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
GMATGuruNY posted a reply to The average (arithmetic mean) of the five numbers in a data in the Problem Solving forum
“Sum = (quantity)(average). The average (arithmetic mean) of the five numbers in a data set is 72. Sum = 5*72 = integer with a UNITS DIGIT OF 0. The average (arithmetic mean) of the first three numbers is 98. Sum = 3*98 = integer with a UNITS DIGIT OF 4. For the sum of all 5 numbers to ...”
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
GMATGuruNY posted a reply to Linda and Angela contract to paint a neighbor's house. Even in the Problem Solving forum
“Let the pay rate = $1 per hour. Let Angela''s time = 4 hours. Since Linda works 50% longer, Linda''s time = 4 + (1/2)4 = 6 hours. Since a total of 10 hours are worked at a rate of $1 per hour, the total pay = 10*1 = $10. Since each worker receives m dollars of the total pay, m=$5. Since ...”
August 23, 2018
GMATGuruNY posted a reply to United Telephone charges a base rate of $10.00 for service, in the Problem Solving forum
“An alternate approach is to PLUG IN THE ANSWERS. When the correct answer is plugged in, the two companies will charge the same amount. B: 10 minutes Since United charges $10 plus $0.25 per minute, the charge from United = 10 + 10(0.25) = $12.50. Since Atlantic charges $12 plus $0.20 per ...”
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
GMATGuruNY posted a reply to A whole number greater than 1 has remainders of 1 when it is in the Problem Solving forum
“We can PLUG IN THE ANSWERS. To yield a remainder of 1 when divided by 4, the correct answer must be 1 more than a multiple of 4. The smallest answer choice that is 1 more than a multiple of 4 is 61. When 61 is divided by 2, 3 or 5, the remainder is 1 in each case. The correct answer is C.”
August 23, 2018
GMATGuruNY posted a reply to One woman and one man can build a wall together in two hours in the Problem Solving forum
“One woman and one man can build a wall together in two hours, but the woman would need the help of two girls in order to complete the same job in the same amount of time. Since replacing 1 man with 2 girls does not change the amount of time required to complete the job, 1 man is the equivalent of 2 ...”
August 23, 2018
GMATGuruNY posted a reply to What is the decimal equivalent of (1/5)^5? in the Problem Solving forum
“1/5⁵ = = (1/25)(1/25)(1/5) = (4/4 * 1/25)(4/4 * 1/25)(2/2 * 1/5) = (4/100)(4/100)(2/10) = 32/100000 = 32 * 10ˉ⁵ = 0.00032 The correct answer is A.”
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
“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
GMATGuruNY posted a reply to While it costs about the same in the Sentence Correction forum
“Correct! OA: The cost of running nuclear power plants is about the same as is the cost] for other types of power plants. The blue verb in brackets is omitted but implied.”
August 22, 2018
GMATGuruNY posted a reply to Five friends Alastair, Bell, Cook, Darren and Eoin appeared in the Problem Solving forum
“To determine the ratio of the scores, plug in numbers and reduce the resulting ratio as much as possible. Let A = Alastair, B = Bell, C = Cook, D = Darren, and E = Eoin. Let B = the product of the denominators = 2*5*5*2 = 100. Darren’s score was 3/2 times that of Bell’s score. D = 3/2(B) = ...”
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
GMATGuruNY posted a reply to While it costs about the same in the Sentence Correction forum
“The OA implies the following: The cost of running nuclear power plants is about the same as for other types of power plants. The prepositions phrase in blue serves the same function as the prepositional phrase in red: both serve to modify the cost.”
August 21, 2018
GMATGuruNY posted a reply to While it costs about the same in the Sentence Correction forum
“to run for X implies that X is a GOAL. Mary plans to run for president. Conveyed meaning: The office of president = Mary''s goal. Thus, to run for other types of power plants implies that OTHER TYPES OF POWER PLANTS constitute a goal. Not the intended meaning. No one is attempting to reach ...”
August 21, 2018
GMATGuruNY posted a reply to While it costs about the same in the Sentence Correction forum
“OA: The cost of running nuclear power plants is about the same as for other types of power plants. Since the blue portion provides its own referent (other types of power plants), the referent in the red portion (nuclear power plants) is not implied in the blue portion. C: It costs about the ...”
August 21, 2018
GMATGuruNY posted a reply to If x and y are prime numbers, how many factors has x^2y^2? in the Data Sufficiency forum
“To count the positive factors of a positive integer: 1. Prime-factorize the integer 2. Write the prime-factorization in the form (a^p)(b^q)(c^r)... 3. The number of factors = (p+1)(q+1)(r+1)... Generally, GMAT problems about factors are constrained to POSITIVE factors. On the GMAT, the posted ...”
August 21, 2018
GMATGuruNY posted a reply to One machine, working at a constant rate, can fill a certain in the Problem Solving forum
“Time and rate have a RECIPROCAL RELATIONSHIP. If Mary works TWICE as fast as John, Mary''s time will be 1/2 John''s time. If Mary works THREE TIMES as fast as John, Mary''s time will be 1/3 John''s time Since 4 machines will work 4 times as fast as 1 machine, the time for 4 machines will ...”
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
GMATGuruNY posted a reply to Which of the following is the best approximation for 11^11-9 in the Problem Solving forum
“Another approach: 10¹¹ (100,000,000,000) is 100 TIMES the value of 10⁹ (1,000,000,000). Implication: 11¹¹ must be MORE THAN 100 TIMES the value of 9⁹. Since 9⁹ is so small when compared to 11¹¹, we can ignore the value of 9⁹ when we approximate: 11¹¹ - 9⁹ ≈ 11¹¹ The ...”
August 21, 2018
GMATGuruNY posted a reply to Which of the following is the best approximation for 11^11-9 in the Problem Solving forum
“Since the answer choices are very spread out, our approximation does not have to very exact. 11¹¹−9⁹ = 11¹¹− (11−2)⁹ ≈ 11¹¹ − 11⁹ = 11⁹(11²−1) ≈ (11⁹)(11²) = 11¹¹ The correct answer is D.”
August 21, 2018
GMATGuruNY posted a reply to Of 30 applicants for a job, 14 had at least 4 years' in the Problem Solving forum
“One approach is to use the following equation: Total = Group 1 + Group 2 - Both + Neither The big idea is to SUBTRACT THE OVERLAP. In the problem above, there is an overlap between the applicants with at least 4 years'' experience and the applicants with degrees. Some applicants belong to BOTH ...”
August 21, 2018
GMATGuruNY posted a reply to Which of the following points could lie in the same quadrant in the Problem Solving forum
“Every answer choice includes at least one negative sign. Test coordinate pairs that include at least one negative value. Case 1: a=1 and b=-1, so that (a, b) = (1, -1) Plug a=1 and b=-1 into the answer choices to see whether one of the answer choices yields a point in the same quadrant as ...”
August 21, 2018
GMATGuruNY posted a reply to If a and b are positive integers and x = 4^a and y = 9^b, in the Problem Solving forum
“x is equal to a POWER OF 4: 4, 16, 64... y is equal to a POWER OF 9: 9, 81... If x=4 and y=81, then xy = 324, which has a units digit of 4. The correct answer is B.”
August 21, 2018
GMATGuruNY posted a reply to Is z an even integer? in the Data Sufficiency forum
“Statement 1: Make a list of options for z/2: z/2 = 0, 2, 4, 6, 8... To get a list of options for z, multiply every value by 2: z = 0, 4, 8, 12, 16... In every case, z is an even integer, so the answer to the question stem is YES. SUFFICIENT. Statement 2: Make a list of options for 3z: 3z ...”
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
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
“GIVEN: The median of a data set is x, and its MAXIMUM is 40 The range of the set is 10 greater than the median So, the range = x + 10 Let N = the MINIMUM value We can write: MAXIMUM value - MINIMUM value = range Rewrite as: 40 - N = x + 10 What is the minimum of the set in terms of x? ...”
August 20, 2018
Brent@GMATPrepNow posted a reply to Let z be the harmonic mean of x and y. If 1/z=(1/2)((1/x)+ in the Problem Solving forum
“Aside: The GMAT doesn''t expect test-takers to know the term harmonic mean. If there were ever a question involving harmonic mean, the definition of the term would be included. Here''s the definition: https://www.investopedia.com/terms/h/harmonicaverage.asp Cheers, Brent”
August 20, 2018
Brent@GMATPrepNow posted a reply to If (|x|-2)(x-1)=0, then x=? in the Data Sufficiency forum
“Target question: What is the value of x? Given: (|x| - 2)(x - 1) = 0 This tells us that EITHER: |x| - 2 OR x - 1 = 0 If |x| - 2 = 0, then x = 2 OR x = -2 If x - 1 = 0, then x = 1 So, there are 3 possible values of x: i. x = 2 ii. x = -2 iii. x = 1 Statement 1: x > 0 When we ...”
August 20, 2018
GMATGuruNY posted a reply to Set S consists of all prime integers less than 10 in the Problem Solving forum
“It is not possible for the two products -- that of the two chosen numbers and that of the two unchosen numbers -- to be equal. Each of the two products has the same probability of being greater. Thus, the probability that the product of the two chosen numbers is greater = 1/2. The correct ...”
August 20, 2018
Brent@GMATPrepNow posted a reply to For the list of numbers above there is exactly one mode. Is in the Data Sufficiency forum
“Sorry, but I don''t see any numbers above.”
August 19, 2018
Brent@GMATPrepNow posted a reply to A line has a slope of 3/4 and intersects the point (-12, -39 in the Problem Solving forum
“TIP: If you were running short on time and encountered this question, you could quickly eliminate C, D and E and guess between A and B . The coordinates of the x-intercept must be in the form (k, 0). So, we can eliminate C, D and E. Now onto the solution... Let''s write the equation in slope ...”
August 19, 2018
Brent@GMATPrepNow posted a reply to If x and y are positive, what is x+y? in the Data Sufficiency forum
“-------------ASIDE-------------------------------- IMPORTANT: We are not told that x and y are integers. So, they need not be integers! ALSO IMPORTANT: There exists a value of y so that 3^y = 36. How do we know this? Well, 3^3 = 27 and 3^4 = 81 Since 36 is BETWEEN 27 and 81, there must be a ...”
August 19, 2018
Brent@GMATPrepNow posted a reply to For the list of numbers above there is exactly one mode. Is in the Data Sufficiency forum
“I don''t see the list of numbers.”
August 19, 2018
Brent@GMATPrepNow posted a reply to R is the set positive odd integers less than 50, and S is in the Problem Solving forum
“How many elements does the intersection of R as S contain? So, we need to count all values that satisfy both conditions In other words, we need to count all values that are BOTH odd integers less than 50 AND the squares of integers Let''s list possible values: 1² = 1 1 is less than ...”
August 19, 2018
GMATGuruNY posted a reply to How many days after the purchase of product X does its in the Data Sufficiency forum
“Statement 1: Minimum number of days: purchase date = January 31, expiration date = March 1 Here, the expiration date = (28 days of February) + (first day of March) = 29 days after purchase. Maximum number of days: purchase date = January 1, expiration date = March 31 Here, the expiration date ...”
August 19, 2018
GMATGuruNY posted a reply to Collectively, the five children in the Kramer family have 30 in the Problem Solving forum
“In ascending order, let the 5 trophy values be a, b, c, d and e. To maximize the value of d -- the second highest value -- we must MINIMIZE the values of a, b and c. Since every child must have a different number of trophies, the least possible values for a, b and c are a=1, b=2, and c=3. Since ...”
August 18, 2018
GMATGuruNY posted a reply to Mona and Donald fly to Rome for the weekend. They take cash in the Problem Solving forum
“We can PLUG IN THE ANSWERS, which represent the total number of notes. The number of €10 notes they take is double the number of $10 notes they take. Thus, the ratio of €10 notes to $10 notes = 2:1. Since the sum of the parts of this ratio = 2+1 = 3, the total number of notes must be a ...”
August 18, 2018
Brent@GMATPrepNow posted a reply to What is the 777th decimal digit of 0.345634563456……..? in the Problem Solving forum
“Look for a pattern... 1st decimal digit: 3 2nd decimal digit: 4 3rd decimal digit: 5 4th decimal digit: 6 5th decimal digit: 3 6th decimal digit: 4 7th decimal digit: 5 8th decimal digit: 6 9th decimal digit: 3 ...etc This pattern repeats itself every 4 digits In other words, the ...”
August 17, 2018
Brent@GMATPrepNow posted a reply to If x, y, and z are positive integers, x=? in the Data Sufficiency forum
“ Given: x, y, and z are positive integers Target question: What is the value of x? Statement 1: y = x + 1, and z = x + 3 There are infinitely many solutions to the above equations, which means there are infinitely many possible answers to the target question. Since we cannot answer the ...”
August 17, 2018
Brent@GMATPrepNow posted a reply to Is x > y? in the Data Sufficiency forum
“Target question: Is x > y? Statement 1: x - y > 3 At first glance, this information APPEARS to be insufficient. However, if we recognize that 3 > 0, then we can add this to the inequality to get: x - y > 3 > 0 From here, we can ignore the 3 to see that: x - y > 0 Add y ...”
August 17, 2018
Brent@GMATPrepNow posted a reply to A certain junior class has 1,000 students and a certain 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, ...”
August 17, 2018
GMATGuruNY posted a reply to A certain junior class has 1,000 students and a certain in the Problem Solving forum
“P(sibling pair) = (total number of sibling pairs)/(total number of possible pairs). Total number of possible pairs: There are 1000 juniors and 800 seniors. Total number of ways to combine 1 junior with 1 senior = 1000*800 = 800,000. Total number of sibling pairs = 60. Thus: ...”
August 17, 2018
Brent@GMATPrepNow posted a reply to A case contains c cartons. Each carton contains b boxes, and in the Problem Solving forum
“Let''s solve this question by picking some numbers (aka using the INPUT-OUTPUT approach). Let b = 3 and c = 5 So, a case contains 5 cartons. Each carton contains 3 boxes, and each box contains 100 paper clips. So, the number of paper clips in 1 case = (100)(5)(3) = 1500 How many paper ...”
August 16, 2018
Brent@GMATPrepNow posted a reply to Over the course of a single week, the price of a company's in the Problem Solving forum
“Let''s assign a "nice" value to the original price. Let $100 be the original price (BEFORE any increases) Over the course of a single week, the price of a company’s stock rose by 10%. 10% of $100 = $10 So, the NEW price = $100 + $10 = $110 The following week the company’s ...”
August 16, 2018
GMATGuruNY posted a reply to Jason can stack two shelves in 3 hours and Maria can stack in the Problem Solving forum
“Let each shelf = 6 pounds. Since Jason takes 3 hours to stack 2 6-pound shelves -- for a total of 12 pounds -- Jason''s rate = 12/3 = 4 pounds per hour. Since Maria takes 2 hours to stack 3 6-pound shelves -- for a total of 18 pounds -- Maria''s rate = 18/2 = 9 pounds per hour. Total weight of 13 ...”
August 16, 2018
GMATGuruNY posted a reply to GPREP 3 SC-9 in the Sentence Correction forum
“Fixed! Thanks for catching the typo.”
August 16, 2018
Brent@GMATPrepNow posted a reply to In a stack of boards at a lumber yard, the 20th board in the Problem Solving forum
“Let''s start from the bottom and work our way up: We''ll start with the 16th board counting from the bottom of the stack Right BELOW that 16th board, we have a board that we''ll call Larry. So, Larry is the 15th board counting from the bottom of the stack. So, starting from the bottom and ...”
August 16, 2018
GMATGuruNY posted a reply to Is n an integer less than 5? in the Data Sufficiency forum
“Statement 1: Make a list of options for 5n: 5n = 1, 2, 3, 4, 5... To get a list options for n, divide every value above by 5: n = 1/5, 2/5, 3/5, 4/5, 1... If n = 1/5, the answer to the question stem is NO. If n = 1, the answer to the question stem is YES. INSUFFICIENT. Statement 2: Make a ...”
August 16, 2018
GMATGuruNY posted a reply to A company hired a printer to produce a total of x + 1 in the Problem Solving forum
“The company requested 3 more 2¢ envelopes than 5¢ envelopes. Let the number of 5¢ envelopes = 2, and the number of number of 2¢ envelopes = 2+3 = 5, with the result that the cost of the envelopes = (5*2) + .(2*5) = 20 cents. A company hired a printer to produce a total of x + 1 envelopes. ...”
August 16, 2018
GMATGuruNY posted a reply to A librarian has a set of ten books, including four different in the Problem Solving forum
“Since the 4 Lincoln books must be side-by-side, place them in a BLOCK: C.”
August 16, 2018
GMATGuruNY posted a reply to A vending machine randomly dispenses four different types in the Problem Solving forum
“There are twice as many strawberry candies as grape candies. If G=1, then S=2. There are twice as many apple candies as strawberry candies. If S=2, then A=4. There are twice as many apple candies as orange candies. If A=4, then O=2. Resulting ratio: G:S:A:O = 1:2:4:2. Since the sum of the ...”
August 16, 2018
GMATGuruNY posted a reply to Three copying machines A, B, and C, working together at in the Problem Solving forum
“Let the job = 8 pages. Since A+B+C take 2 hours to copy the 8-page job, the combined rate for A+B+C = 8/2 = 4 pages per hour. Since B+C take 4 hours to copy the 8-page job, the combined rate for B+C = 8/4 = 2 pages per hour. A''s rate = (rate for A+B+C) - (rate for B+C) = 4-2 = 2 pages per ...”
August 15, 2018
GMATGuruNY posted a reply to (x – 1)(y – 1) = 1? in the Data Sufficiency forum
“Alternate approach: Statement 1: Case 1: x=2 Substituting x=2 into x+y = xy, we get: 2 + y = 2y 2 = y. In this case, (x-1)(y-1) = (2-1)(2-1) = 1, so the answer to the question stem is YES. Case 2: x=3 Substituting x=3 into x+y = xy, we get: 3+ y = 3y 3 = 2y 3/2 = y. In this case, ...”
August 15, 2018
GMATGuruNY posted a reply to Students are in clubs as follows: Science-20, Drama-30, and in the Problem Solving forum
“When we count the total in Science, the total in Drama, and the total in Band, any students in exactly two of the clubs are counted TWICE. Thus, we must SUBTRACT these students so that they are not double counted: Total = Science + Drama + Band - (exactly 2 clubs) = 20 + 30 + 12 - (8+6+4) = 44. ...”
August 15, 2018
Brent@GMATPrepNow posted a reply to A rectangular box, with dimesions of 12 inches by 18 inches in the Problem Solving forum
“The question comes down to determining how to orient the box. Do, we make the HEIGHT of the box 12 inches, 18 inches or 10 inches? Well, since the height of each CAN is 5 inches, we can see that making the HEIGHT of the box 10 inches is a great course of action. Otherwise, there will be empty ...”
August 15, 2018
Brent@GMATPrepNow posted a reply to (x – 1)(y – 1) = 1? in the Data Sufficiency forum
“ Given: xy > 0 Target question: Does (x - 1)(y - 1) = 1? This is a good candidate for rephrasing the target question Take the equation: (x - 1)(y - 1) = 1 Use FOIL to expand the left side to get: xy - x - y + 1 = 1 Subtract 1 from both sides to get: xy - x - y = 0 REPHRASED ...”
August 15, 2018
Brent@GMATPrepNow posted a reply to For all real numbers x and y, let x# y = (xy)^2 − x + y^2 in the Problem Solving forum
“APPROACH #2 - Test the answer choices A) 0 Take x#y = (xy)² − x + y², and replace y with 0 We get: 0)]² − x + 0² = 0, x#y = -x PERFECT! Answer: A Cheers, Brent”
August 15, 2018
Brent@GMATPrepNow posted a reply to For all real numbers x and y, let x# y = (xy)^2 − x + y^2 in the Problem Solving forum
“APPROACH #1 We want the following equation to hold true: x # y = –x Replace x # y with its equivalent to get: (xy)² − x + y² = -x Add x to both sides to get: (xy)² + y² = 0 Simplify (xy)² to get: x²y² + y² = 0 Factor out the y² to get: y²(x² + 1) = 0 So, the equation will hold ...”
August 15, 2018
Brent@GMATPrepNow posted a reply to Uncle Bruce is baking chocolate chip cookies. He has 36 in the Problem Solving forum
“We can also use equivalent ratios The cookies will consist of 20% chocolate. In other words, the cookies will consist of 1/5 chocolate. We can also say the cookies will consist of 4/5 dough. This means the cookies are 4 parts dough and 1 part chocolate. So, the dough to chocolate ratio ...”
August 15, 2018
GMATGuruNY posted a reply to Uncle Bruce is baking chocolate chip cookies. He has 36 in the Problem Solving forum
“= Since chocolate must constitute 20% of the cookies, the 36 ounces of dough must constitute the remaining 80%: 36 = 0.8x x = 36/0.8 = 360/8 = 45 ounces. Since the cookies = 45 ounces, and the dough = 36 ounces, the amount of chocolate used = 45-36 = 9 ounces. Thus -- of the 15 ounces of ...”
August 15, 2018
Brent@GMATPrepNow posted a reply to If mn ≠ 0 and 25 percent of n equals in the Problem Solving forum
“Useful conversions: 25% = 1/4 37.5% = 3/8 25 percent of n equals 37(1/2) percent of m In other words, 1/4 of n equals 3/8 of m We get: (1/4)(n) = (3/8)(m) Simplify: n/4 = 3m/8 What is the value of 12n/m? Take n/4 = 3m/8 Cross-multiply to get: (8)(n) = (3m)(4) Simplify: 8n = 12m ...”
August 15, 2018
GMATGuruNY posted a reply to Three printing presses, R, S, and T, working together at the in the Problem Solving forum
“Let the job = 20 pages. Since R+S+T take 4 hours to print the 20-page job, the combined rate for R+S+T = 20/4 = 5 pages per hour. Since S+T take 5 hours to print the 20-page job, the combined rate for S+T = 20/5 = 4 pages per hour. R''s rate = (rate for R+S+T) - (rate for S+T) = 5-4 = 1 page per ...”
August 14, 2018
Brent@GMATPrepNow posted a reply to John sold 100 shares of stock for $96 per share. For half in the Problem Solving forum
“Let x be the ORIGINAL price of each share that sold for a 20% PROFIT So, 1.2x = price of each share that sold for a 20% profit In other words, 1.2x = $96 So, x = 96/1.2 = $80 So, these shares ORIGINALLY cost $80 each Let y be the ORIGINAL price of each share that sold for a 20% LOSS So, 0.8x ...”
August 14, 2018
Brent@GMATPrepNow posted a reply to Three printing presses, R, S, and T, working together at the in the Problem Solving forum
“----------ASIDE-------------------- 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 ...”
August 14, 2018
Brent@GMATPrepNow posted a reply to Which of the following lines in the xy-plane does not in the Problem Solving forum
“Core concept: If a point (x,y) is on a given line, then the coordinates (x and y) of that point must satisfy the equation of that line. In answer choice B, the equation (y = x + 1/2) tells us that, for ANY POINT ON THE LINE, the y-coordinate will be equal to the x-coordinate plus 1/2 So, if the ...”
August 14, 2018
Brent@GMATPrepNow posted a reply to If a number between 0 and 1 is selected at random, which of in the Problem Solving forum
“Another approach is to convert everything to decimals We need to determine the LENGTH OF EACH INTERVAL. The interval that has the greatest length, will be the most likely interval. To determine the length of each interval, it may be faster to first convert the fractions to decimals. We get: ...”
August 14, 2018
GMATGuruNY posted a reply to If a number between 0 and 1 is selected at random, which of in the Problem Solving forum
“Put the ranges over the same DENOMINATOR: A: 0 and 3/20 B. 30/20 and 1/5 -- 3/20 and 4/20 C. 1/5 and 1/4 --> 4/20 and 5/20 D. 1/4 and 3/10 --> 5/20 and 6/20 E. 3/10 and 1/2 --> 6/20 and 10/20 Since the greatest range is offered by E (10/20 - 6/20 = 4/20), the number is most likely ...”
August 14, 2018
Brent@GMATPrepNow posted a reply to Challenge: If f(3x + 2) = 9x² + 12x - 1, then f(k - 1) = in the Problem Solving forum
“Given: f(3x + 2) = 9x² + 12x - 1 First notice that 9x² + 12x - 1 looks a lot like how (3x + 2)² looks when we expand an simplify it. Notice that (3x + 2)² = 9x² + 12x + 4 This is VERY similar to 9x² + 12x - 1 In fact, if we take 9x² + 12x + 4 and subtract 5, we get 9x² + 12x - 1 That ...”
August 14, 2018
Brent@GMATPrepNow posted a reply to Ben is driving on the highway at x miles per hour. (One mile in the Problem Solving forum
“Here''s an algebraic approach: Each tire has a circumference of y feet. So, there will be 1 revolution every time the car travels y feet. 5280/y = the number of times y divides into 5280. So, if the car travels 5280 feet (aka 1 mile) in one hour, then there will be 5280/y revolutions. If ...”
August 14, 2018
GMATGuruNY posted a reply to Lyme disease is caused by a bacterium transmitted to humans in the Critical Reasoning forum
“E, rephrased as a basic statement: The other species on which deer tick larvae feed harbor other bacteria that ticks transmit to humans. The conclusion is constrained to the number of ticks infected with the bacterium that causes LYME DISEASE. Information about other bacteria is irrelevant ...”
August 14, 2018
GMATGuruNY posted a reply to Ben is driving on the highway at x miles per hour. (One mile in the Problem Solving forum
“Note: One revolution = one CIRCUMFERENCE. Let x = 2 miles per hour, implying that the distance traveled in 1 hour = 2*5280 = 10560 feet. Let y = 10 feet. Since the total distance traveled in 1 hour = 10560 feet, and each circumference = 10 feet, the number of revolutions in 1 hour = 10560/10 = ...”
August 14, 2018
GMATGuruNY posted a reply to Bob invests 100 dollars in a fund that yileds 15% simple in the Problem Solving forum
“Alternate approach: To earn exactly $100 in interest at rate of $15 earned each month, the number of months required = 100/15 = 20/3 = 6.66 months. The smallest integer greater than 6.66 is 7. Implication: After 7 months, the total amount of interest will for the first time EXCEED $100, with ...”
August 14, 2018
GMATGuruNY posted a reply to When x is divided by 2, the remainder is 1 and y is divided in the Problem Solving forum
“Algebraic approach: When x is divided by 2, the remainder is 1. In other words, x is a multiple of 2 plus 1: x = 2a + 1. When y is divided by 8, the remainder is 2. In other words, y is a multiple of 8 plus 2: y = 8b + 2. Thus: 2x + y = 2(2a+1) + (8b + 2) = 4a + 2 + 8b + 2 = 4a + 8b + ...”
August 14, 2018
GMATGuruNY posted a reply to Stacy and Katie plan to walk the 27-mile scenic route across in the Problem Solving forum
“Since Stacy and Katie travel toward each other, they WORK TOGETHER to cover the 27 miles between them. Since Stacy is 1/4 faster than Katie, for every 4 miles that Katie travels, the distance traveled by Stacy = 4 + (1/4)(4) = 5 miles. Thus, of every 9 miles traveled when Stacy and Katie work ...”
August 14, 2018
beatthegmat posted a new topic called Prepping for the GMAT Is a Marathon, Not a Sprint in the GMAT Strategy forum
“https://s15.postimg.cc/a2pix60fr/image.png The Graduate Management Admissions Test, or GMAT, is a common admissions requirement for most MBA programs, especially for applicants who don’t have a lot of work experience. The GMAT is a long and difficult exam that tests your command of the English ...”
August 13, 2018
Brent@GMATPrepNow posted a reply to If x is the sum of six consecutive integers, the x is in the Problem Solving forum
“Let''s test some possible values.... The six consecutive integers COULD be 1, 2, 3, 4, 5, 6 So, the SUM = 1 + 2 + 3 + 4 + 5 + 6 = 21 Now check the three statements.... I. 3 21 IS divisible by 3 So, statement 1 is TRUE. ELIMINATE B and C II. 4 21 is NOT divisible by 3 So, ...”
August 13, 2018
Brent@GMATPrepNow posted a reply to A machine at the golf ball factory can produce 16 golf balls in the Problem Solving forum
“Let''s answer the question in steps... GIVEN: 1 machine produces 16 golf balls in 5 minutes. So, 1 machine produces 16/5 golf balls in 1 minute So, 5 machines produce 16 golf balls in 1 minute So, 10 machines produce 32 golf balls in 1 minute Answer: D Cheers, Brent”
August 13, 2018
GMATGuruNY posted a reply to If the average of 993, 994, 996, 997, 998, 1001, 1001, 1002, in the Problem Solving forum
“Sum of the 10 terms = (quantity)(average) = 10*999 = 9990. If we add the units digits of the nine given terms, we get: 3+4+6+7+8+1+1+2+4 = 36. The sum of the nine given terms has a units digit of 6. The sum of all ten terms has a units digit of 0. Since (units digit of 6) + (units digit of 4) = ...”
August 12, 2018
Brent@GMATPrepNow posted a new topic called Challenge: If f(3x + 2) = 9x² + 12x - 1, then f(k - 1) = in the Problem Solving forum
“If f(3x + 2) = 9x² + 12x - 1, then f(k - 1) = A) k² - 2k - 6 B) k² - 2k - 5 C) k² - 2k - 4 D) k² - 2k + 1 E) k² - 2k + 5 Answer: C Difficulty level: 700+ Source: www.gmatprepnow.com * I''ll post a solution in 2 days”
August 12, 2018
Brent@GMATPrepNow posted a new topic called If f(2x - 1) = 4x² - 4x - 8, then f(5) = in the Problem Solving forum
“If f(2x - 1) = 4x² - 4x - 8, then f(5) = A) 16 B) 18 C) 36 D) 48 E) 72 Answer: A Difficulty level: 600 (ish) Source: www.gmatprepnow.com”
August 12, 2018
Brent@GMATPrepNow posted a reply to Are all of the terms in Set A equal? in the Data Sufficiency forum
“Target question: Are all of the terms in Set A equal? Statement 1: The sum of all 14 terms in Set A is 98 There are several possible scenarios that satisfy this statement. Here are two. Case a: Set A = {7,7,7,7,7,7,7,7,7,7,7,7,7,7} in which case all of the numbers ARE equal Case b: Set A = ...”
August 12, 2018
Brent@GMATPrepNow posted a reply to A box contains only red chips, green chips and blue chips. in the Data Sufficiency forum
“Target question: What is the probability that the chip is either red or green? Given: The box contains only red chips, green chips and blue chips Statement 1: The probability of selecting green chip is 1/3 This tells us that 1/3 of the chips are GREEN, but there''s no information about ...”
August 12, 2018
GMATGuruNY posted a reply to Are all of the terms in Set A equal? in the Data Sufficiency forum
“I posted a solution to a very similar problem here: https://www.beatthegmat.com/from-og-12-t73239.html”
August 12, 2018
Brent@GMATPrepNow posted a reply to At a certain university, the dormitory policy is that each in the Problem Solving forum
“One approach is to use equivalent ratios Each dormitory must have at least 7 resident advisers for every 200 residents. So, advisers/residents = 7/200 If a dormitory is home to 3500 residents, what is the minimum number of resident advisers required? Let x = minimum number of advisers We ...”
August 11, 2018
Brent@GMATPrepNow posted a reply to A retailer orders u units of an item for which he pays d in the Problem Solving forum
“A retailer orders u units of an item for which he pays d dollars. So, EACH unit costs d/u dollars However, he mistakenly receives u - 3 items. In other words, he received 3 fewer units than he wanted So, he paid for 3 units that he never received (i.e., he was overcharged for 3 units) How ...”
August 11, 2018
Brent@GMATPrepNow posted a reply to A card game called “high-low” divides a deck of 52 playi in the Problem Solving forum
“Once we recognize that we can achieve 5 points by drawing 3 Low cards and 1 High card, then it really comes down to determining the number of ways to rearrange 3 L''s and 1 H. One option is to simply list the arrangements. Alternatively, we can use the MISSISSIPPI rule, which says: If there are ...”
August 11, 2018
GMATGuruNY posted a reply to profit and loss in the Problem Solving forum
“Let r=0, implying that no profit is made and that the oranges are sold at cost. Let q=12, implying that the cost for 12 oranges is $12, with the result that the cost per orange = $1. 1.66 dozen = (5/3)(12) = 20 oranges. Since the cost for 20 oranges = $20, p=20. Thus: 5pq - 12r = (5*20*12) - ...”
August 11, 2018
GMATGuruNY posted a reply to In each game of a certain tournament, a contestant either in the Data Sufficiency forum
“Here is an algebraic way to combine the two statements: Let G = a game that results in a 2-point gain and L = a game that results in a 3-point loss. Statement 1: Since the played games yield a total of 4 points beyond the intital 100 points, we get: 2G - 3L = 4 2G = 4 + 3L Note: Since the ...”
August 10, 2018
Brent@GMATPrepNow posted a reply to In each game of a certain tournament, a contestant either in the Data Sufficiency forum
“Target question: How many games did Pat play in the tournament? Jump straight to... Statements 1 and 2 combined There are several CONFLICTING situations that that satisfy BOTH statement 2. Here are two: Case a: Pat plays 2 games and wins both of them to add 4 points to the 100 points ...”
August 10, 2018
Brent@GMATPrepNow posted a reply to In a home library consisting of 108 books, some hardcover in the Problem Solving forum
“The concept tested here is the same as is tested in this official GMAT question: https://www.beatthegmat.com/og-help-problem-t286349.html Give it a try. Cheers, Brent”
August 10, 2018
GMATGuruNY posted a reply to In a home library consisting of 108 books, some hardcover in the Problem Solving forum
“Goal: To MAXIMIZE the number of nonfiction books. Since the fraction of hardcover books that are nonfiction (2/3) is greater than the fraction of softcover books that are nonfiction (1/4), the number of nonfiction books will be maximized if we must MAXIMIZE THE NUMBER OF HARDCOVER BOOKS. ...”
August 10, 2018
Brent@GMATPrepNow posted a reply to A family consisting of one mother, one father, two daughters in the Problem Solving forum
“Another (slightly longer) approach: The restriction about the sisters is somewhat problematic, so let''s IGNORE the rule and seat all 5 people without obeying that restriction. Then once I determine the total number of arrangements, I''ll subtract the number of arrangements where the sisters ...”
August 10, 2018
GMATGuruNY posted a reply to A family consisting of one mother, one father, two daughters in the Problem Solving forum
“Case 1: One daughter in the front passenger seat: Since one of the 2 parents must drive, number of choices for the driver''s seat = 2. Since either of the 2 daughters can be in the front passenger seat, number of choices = 2. Number of ways to arrange the 3 remaining people = 3! = 6. To combine ...”
August 10, 2018
GMATGuruNY posted a reply to mgmat 4 in the Data Sufficiency forum
“Fixed! Thanks for pointing out the typo.”
August 10, 2018
Brent@GMATPrepNow posted a reply to How many different 3-digit numbers are greater than 299 and in the Problem Solving forum
“Take the task of creating the 3-digit numbers and break it into stages. Stage 1: Select the first digit (hundreds digit) Since the first digit can be 3, 4, 5, 7 or 9, we can complete stage 1 in 5 ways Stage 2: Select the second digit (tens digit) Since the second digit can be 0, 2, 3, 4, ...”
August 10, 2018
Brent@GMATPrepNow posted a reply to A sports team played 100 games last season. Did this team in the Data Sufficiency forum
“Target question: Did this team win at least half of the games it played last season? Rephrased target question: Did this team win more than 49 games? Statement 1: The team won 60% of its first 65 games In other words, the team won 39 of its first 65 games Since we don''t know the results ...”
August 9, 2018
Brent@GMATPrepNow posted a reply to Problem Solving on Set Theory 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 baseball players, and the two characteristics ...”
August 9, 2018
Brent@GMATPrepNow posted a reply to If the average (arithmetic mean) of a, b and c is m, is thei in the Data Sufficiency forum
“Target question: Is the standard deviation of a, b and c less than 1? Statement 1: a, b and c are consecutive integers with a < b < c. It''s important to know that standard deviation is a measure of dispersion (how spread apart the values are). So, ANY 3 consecutive integers will have ...”
August 8, 2018
Brent@GMATPrepNow posted a reply to Extra practice with ratios: A certain zoo has exactly five in the Problem Solving forum
“The ratio of the number of alligators to buffalo to camels is 4 : 3 : 1 So we can write: , A : B : C = 4 : 3 : 1 The ratio of the number deer to elephants to buffalo is 6 : 1 : 4 So we can write: D : E : B = 6 : 1 : 4 Notice that both ratios have a B in common. In order to COMBINE the two ...”
August 8, 2018
Brent@GMATPrepNow posted a reply to There is at least one red bal and at least one blue ball in in the Data Sufficiency forum
“Statement 1 indirectly tells us that it''s IMPOSSIBLE to select 2 blue balls. So, the box must contain fewer than 2 blue balls. Since we''re told that the box contains AT LEAST 1 blue ball, we can be certain that there is EXACTLY 1 blue ball. As far a red balls are concerned, all we know for ...”
August 7, 2018
Brent@GMATPrepNow posted a reply to If the speed of X meters per second is equivalent to the in the Problem Solving forum
“We want to convert meters per second to kilometers per hour First, since 1 kilometer = 1000 meters, we can also say that 1 kilometer/1000 meters = 1 Second, since 3600 seconds = 1 hour, we can also say that 3600 seconds/1 hour = 1 This means that multiplying a value by 1 kilometer/1000 meters ...”
August 7, 2018
GMATGuruNY posted a reply to If the speed of X meters per second is equivalent to the in the Problem Solving forum
“Plug in for x a value that is easy to convert from meters to kilometers. Let x = 1000 meters per second. Since 1000 meters = 1 kilometer, this rate = 1 kilometer per second. Since there are 3600 seconds in an hour, 1 kilometer per second = 3600 kilometers per hour. Thus, y = 3600. This is ...”
August 7, 2018
GMATGuruNY posted a reply to If the average (arithmetic mean) of four different numbers in the Data Sufficiency forum
“Sum of the 4 numbers = (quantity)(average) = 4*30 = 120. Statement 1: Case 1: The four numbers are 32, 31, 30, 27 In this case, two of the numbers are greater than 30. Case 2: The four numbers are 33, 32, 31, 24 In this case, three of the numbers are greater than 30. INSUFFICENT. ...”
August 7, 2018
GMATGuruNY posted a reply to During a one day sale, a store sold each sweater of a in the Data Sufficiency forum
“Statement 1: Case 1: 1 sweater is sold for $270 Case 2: 3 sweaters are sold for $90 each Since the number of sweaters sold can be different values, INSUFFICIENT. Statement 2: Since the $30 markup is 1/2 the cost of each sweater, the cost of each sweater = 60. Thus, the selling price of ...”
August 7, 2018
Brent@GMATPrepNow posted a reply to GMAT Official Guide 2019 A prominent investor who holds in the Critical Reasoning forum
“For boldfaced questions, students must be sure to generically summarize the roles that each part plays BEFORE examining the answer choices. Otherwise, it is much more difficult to determine the correct answer. So here''s my generic summary: The first boldfaced part describes the TYPICAL cause ...”
August 7, 2018
Brent@GMATPrepNow posted a reply to Is Hector taller than Charley? in the Data Sufficiency forum
“Target question: Is Hector taller than Charley? Statement 1: Hector is 5 feet 7 inches tall. No information about Charley. Charley COULD be 8 feet tall (i.e., taller than Hector) or Charley COULD be 3 feet tall (i.e., shorter than Hector) Since we cannot answer the target question with ...”
August 7, 2018
Brent@GMATPrepNow posted a reply to In the right triangle shown above, what is the value of a? in the Data Sufficiency forum
“Target question: What is the value of a? Let''s jump straight too.... Statements 1 and 2 combined Statement 1 tells us that c = 5. Statement 2 tells us that a < b There are several values of a, b and c that satisfy BOTH statements. Here are two cases: Case a: a = 3, b = 4 and c = 5. ...”
August 6, 2018
Brent@GMATPrepNow posted a reply to In the right triangle shown above, what is the value of a? in the Data Sufficiency forum
“You''re assuming that a and b are INTEGERS. If that were the case, then C could be the correct answer.”
August 6, 2018
Brent@GMATPrepNow posted a reply to If the operation # is one of the four arithmetic operations- in the Data Sufficiency forum
“Target question: Is (6#2)#4 = 6#(2#4)? This is a good candidate for rephrasing the target question. Under what circumstances does (6#2)#4 = 6#(2#4) ? Let''s test each possible operation: ADDITION: If # represents addition, we get: (6+2)+4 = 6+(2+4) Simplify to get: 12 = 12. WORKS! So, ...”
August 6, 2018
Brent@GMATPrepNow posted a reply to GMAT Official Guide 2019 A company has developed a new in the Critical Reasoning forum
“You might want to revisit your solution here. The official answer is B Cheers, Brent”
August 6, 2018
Brent@GMATPrepNow posted a reply to GMAT Official Guide 2019 A company has developed a new in the Critical Reasoning forum
“PREMISE: New sensor detects signals from beating heart PREMISE: Signals pass through almost everything CONCLUSION: New sensor will help locate trapped people quickly Now let''s examine each answer choice while reminding ourselves of the conclusion. A) Does this strengthen the conclusion ...”
August 6, 2018
Brent@GMATPrepNow posted a reply to A data set with a mean of 60 has a standard deviation of 3.5 in the Problem Solving forum
“-----------ASIDE----------------------- A little extra background on standard deviations above and below the mean If, for example, a set has a standard deviation of 4, then: 1 standard deviation = 4 2 standard deviations = 8 3 standard deviations = 12 1.5 standard deviations = 6 0.25 ...”
August 6, 2018
Brent@GMATPrepNow posted a reply to A data set with a mean of 60 has a standard deviation of 3.5 in the Problem Solving forum
“-----------ASIDE----------------------- A little extra background on standard deviations above and below the mean If, for example, a set has a standard deviation of 4, then: 1 standard deviation = 4 2 standard deviations = 8 3 standard deviations = 12 1.5 standard deviations = 6 0.25 ...”
August 6, 2018
Brent@GMATPrepNow posted a reply to If integer k is equal to the sum of all even multiples of 15 in the Problem Solving forum
“Multiples of 15: 15, 30, 45, 60, 75, 90, 105, etc EVEN multiples of 15: 30, 60, 90, 120, .... So k = 300 + 330 + 360 + ... + 570 + 600 300 = 30(10) 330 = 30(11) 360 = 30(12) 390 = 30(13) . . . 570 = 30(19) 600 = 30(20) So k = 30(10 + 11 + 12 + ... + 19 + 20) ...”
August 6, 2018
Brent@GMATPrepNow posted a reply to If x and y are consecutive odd integers such that x < y, in the Data Sufficiency forum
“Target question: What is the value of y + x? Given: x and y are consecutive odd integers such that x < y Statement 1: The product of xy is negative In order for the product xy to be NEGATIVE, it must be the case that one value is POSITIVE and one value of NEGATIVE. Since x and y are ...”
August 6, 2018
Brent@GMATPrepNow posted a reply to Which of the following CANNOT be the least common multiple in the Problem Solving forum
“Phew! I thought I was going bananas! Obviously not an actual GMATPrep question (as the OP suggests). I wonder what the original answer choice E was. I searched for this post elsewhere, and it appears to have been transcribed like that each time. Cheers, Brent”
August 6, 2018
Brent@GMATPrepNow posted a reply to Each of the 45 boxes on shelf J weighs less than each of the in the Data Sufficiency forum
“Target question: What is the median weight of 89 boxes on these shelves? Given: Each of the 45 boxes on shelf J weighs less than each of the 44 boxes on the shelf K. Let J1 be the weight of the lightest box on shelf J. Let J2 be the weight of the 2nd lightest box on shelf J. . . . Let ...”
August 6, 2018
beatthegmat posted a new topic called MBA Admissions: Tips for International Students in the The Application Process forum
“A large number of MBA students across the globe intend to pursue their degree outside their home country. Are you thinking of studying abroad? The United States, Europe and Canada are home to many of the world’s top-ranked business schools. Consider these tips if you’re hoping to make one of ...”
August 6, 2018
GMATGuruNY posted a reply to Which of the following CANNOT be the least common multiple in the Problem Solving forum
“If x and y are equal, then their LCM = x = y. Thus, x+y can be the LCM of x and y only if x and y are NOT equal. If x+y is the LCM of x and y, then dividing x+y by x or y must yield an INTEGER. If we divide x+y by x. we get: (x+y)/x = x/x + y/x = 1 + y/x. The expression in blue will be an ...”
August 6, 2018
Brent@GMATPrepNow posted a reply to What is the value of integer z? in the Data Sufficiency forum
“Target question: What is the value of integer z? Statement 1: z represents the remainder when positive integer x is divided by positive integer (x – 1) In almost all cases, we will get a remainder of 1 when we divide x by (x-1). For example, 6 divided by 5 equals 1 with remainder 1 (in ...”
August 5, 2018
Brent@GMATPrepNow posted a new topic called Extra practice with ratios: A certain zoo has exactly five in the Problem Solving forum
“A certain zoo has exactly five types of animals: alligators, buffalo, camels, deer and elephants. The ratio of the number of alligators to buffalo to camels is 4 : 3 : 1. The ratio of the number deer to elephants to buffalo is 6 : 1 : 4. Which of the following could represent the total animal ...”
August 5, 2018
Brent@GMATPrepNow posted a reply to What is the remainder when n is divided by 26, given that in the Data Sufficiency forum
“Target question: What is the remainder when n is divided by 26 Given: n divided by 13 gives “a” as the quotient and “b” as the remainder? (a, b and n are positive integers) There''s a nice rule that say, "If N divided by D equals Q with remainder R, then N = DQ + R" For ...”
August 5, 2018
Brent@GMATPrepNow posted a reply to Which of the following CANNOT be the least common multiple in the Problem Solving forum
“Am I going crazy? I was also going to solve this question using the process of elimination. That is, if an answer choice CAN be the least common multiple (LCM) of x and y, then we''ll ELIMINATE that answer choice. (A) If x = 1 and y = 1, then the LCM is 1. Since xy = (1)(1) = 1, we can see ...”
August 5, 2018
GMATGuruNY posted a reply to Which of the following CANNOT be the least common multiple in the Problem Solving forum
“Neither x-y nor x+y can be the LCM of x and y. What is the source of this problem?”
August 5, 2018
GMATGuruNY posted a reply to IF N=5^5*10^10*15^15*20^20*25^25*30^30*35^35*40^40*45^45*50^ in the Problem Solving forum
“This problem is about TRAILING 0''s: the number of 0''s at the end of a large product. Since 10=2*5, EVERY COMBINATION OF 2*5 contained within the prime-factorization of N will yield a 0 at the end of the integer representation of N.. N=5⁵ * 10¹⁰ * 15¹⁵ * 20²⁰ * 25²⁵ * 30³⁰ ...”
August 5, 2018
Brent@GMATPrepNow posted a reply to Which of the following CANNOT be the least common multiple in the Problem Solving forum
“Key Concept: the least common multiple (LCM) of x and y is a multiple of x and a multiple of y. Let''s examine a few multiples: Multiples of 7: 7, 14, 21, 28, 35,... Multiples of 10: 10, 20, 30, 40, 50, 60, ,... Multiples of 3: 3, 6, 9, 12, 15, 18,,... Notice that the multiples of N are ...”
August 5, 2018
GMATGuruNY posted a reply to A contractor combined x tons of a gravel mixture that in the Data Sufficiency forum
“x = 10% gravel y = 2% gravel. z = the MIXTURE of x and y = 5% gravel. To determine the required ratio of x to y, use ALLIGATION -- a very efficient way to handle MIXTURE PROBLEMS. Step 1: Plot the 3 percentages on a number line, with the percentages for x and y on the ends and the ...”
August 4, 2018
Brent@GMATPrepNow posted a reply to A contractor combined x tons of a gravel mixture that in the Data Sufficiency forum
“Let''s use some weighted averages to solve this question Weighted average of groups combined = (group A proportion)(group A average) + (group B proportion)(group B average) + (group C proportion)(group C average) + ... Target question: What is the value of x ? Given: A contractor combined x ...”
August 4, 2018
Brent@GMATPrepNow posted a reply to A certain movie star's salary for each film she makes consis in the Problem Solving forum
“Let F = the fixed amount the star receives for a movie Let p = the percentage of the gross revenue the star receives for a movie The star made $32 million on a film that grossed $100 million So, we can write: F + (p/100)(100) = 32 The star made $24 million on a film that grossed $60 ...”
August 4, 2018
Brent@GMATPrepNow posted a reply to If a and b represent positive single digits in the correctly in the Problem Solving forum
“Units digits first.... 2 + 3 + b yields a sum with units digit 0 So, b = 5 So, the top number and bottom number are now 22 and 45 We have: 22 a3 +45 ___ 90 22 + 45 = 67 So, we have: 67 + a3 = 90 Subtract 67 from both sides to get: a3 = 23 So, a = 2 What is the value of the two ...”
August 4, 2018
Brent@GMATPrepNow posted a reply to A certain junior class has 1,000 students and a certain 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, ...”
August 4, 2018
GMATGuruNY posted a reply to In the figure, angle C and angle M are right angles, and KL in the Data Sufficiency forum
“Statement 1: Since ∠C=∠M=90 and ∠ABC=∠KLM, the remaining two angles are also equal: ∠BAC=∠LKM. Triangles with the same combination of angles are SIMILAR. In similar triangles, corresponding sides in the SAME RATIO. Here, AB and KL are corresponding sides, since each is a ...”
August 4, 2018
GMATGuruNY posted a reply to In the figure, angle C and angle M are right angles, and KL in the Data Sufficiency forum
“Statement 1: Since ∠C=∠M=90 and ∠ABC=∠KLM, the remaining two angles are also equal: ∠BAC=∠LKM. Triangles with the same combination of angles are SIMILAR. In similar triangles, corresponding sides in the SAME RATIO. Here, AB and KL are corresponding sides, since each is a ...”
August 4, 2018
GMATGuruNY posted a reply to A certain junior class has 1,000 students and a certain in the Problem Solving forum
“P(sibling pair) = (total number of sibling pairs)/(total number of possible pairs). Total number of possible pairs: There are 1000 juniors and 800 seniors. Total number of ways to combine 1 junior with 1 senior = 1000*800 = 800,000. Total number of sibling pairs = 60. Thus: ...”
August 4, 2018
GMATGuruNY posted a reply to A software company contracted its sister network in the Data Sufficiency forum
“Statement 1: Case 1: T= 20,000 and L = 10,000, In this case, L/T = 10,000/20,000 = 1/2. Case 2: T = 30,000 and L = 20,000 In this case, L/T = 20,000/30,000 = 2/3. Since L/T can be different values, INSUFFICIENT. Statement 2: In other words, the equipment charge alone is equal to 5/6 of the ...”
August 4, 2018
Brent@GMATPrepNow posted a reply to What is the hundredths digit of th decimal Z? in the Data Sufficiency forum
“Target question: What is the hundredths digit of the decimal z? Statement 1: The tenths digit of 100z is 2 Notice what happens when we take a decimal like 0.123456 and multiply it by 100. We get 12.345 (the tenths digit is 3) In the original decimal, the 3 was in the thousandths place. ...”
August 3, 2018
Brent@GMATPrepNow posted a reply to When a positive integer n is divided by 3, what is the remai in the Data Sufficiency forum
“Target question: What is the remainder when positive integer n is divided by 3? Statement 1: When n is divided by 5, the remainder is 2 -----ASIDE--------------------------------------- When it comes to remainders, we have a nice rule that says: If N divided by D leaves remainder R, then ...”
August 3, 2018
Brent@GMATPrepNow posted a reply to If x^2+y^2=2xy, then (x-y)^2=? in the Problem Solving forum
“APPROACH #2 - Plug in numbers First find values of x and y that satisfy the given information (x² + y² = 2xy) Notice that, when x = 1 and y = 1, the equation, x² + y² = 2xy, holds true. We want to find the value of (x - y)² Plug in x = 1 and y = 1 to get: (x - y)² = (1 - 1)² = 0² = ...”
August 3, 2018
Brent@GMATPrepNow posted a reply to If x^2+y^2=2xy, then (x-y)^2=? in the Problem Solving forum
“APPROACH #1: Algebra Given: x² + y² = 2xy Subtract 2xy from both sides: x² - 2xy + y² = 0 (this should look familiar....it''s a special product) Factor left side: (x - y)(x - y) = 0 In other words, (x - y)² = 0 Answer: C Cheers, Brent”
August 3, 2018
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August 3, 2018
GMATGuruNY posted a reply to What is the hundredths digit of th decimal Z? in the Data Sufficiency forum
“Statement 1: 100z = 0.2, 1.2, 2.2... Dividing every value by 100, we get the following options for z: z = 0.002, 0.012, 0.022... Since the hundredth digit of z can be different values, INSUFFICIENT. Every value in the blue list above also satisfies Statement 2. Thus -- even when the ...”
August 3, 2018
Brent@GMATPrepNow posted a reply to Is the integer x a multiple of 10? in the Data Sufficiency forum
“Yes, -10 and 0 are multiples of 10. We say that N is a multiple of d if we can write N = kd, where k is an integer. So, for example, 24 is a multiple of 8 because we can write 24 = (3)(8), and 3 is an integer. Likewise, -10 is a multiple of 10 because we can write -10 = (-1)(10), and -1 is an ...”
August 2, 2018
Brent@GMATPrepNow posted a reply to Jessica can text 85 words per minute, while Maurice can text in the Problem Solving forum
“Since the answer choices are somewhat spread apart, we can probably use some estimation... Jessica can text 85 words per minute, while Maurice can text 10 words per minute So, COMBINED, they can text 95 words per minute Let''s round this up to 100 words per minute So, the number of words PER ...”
August 2, 2018
Brent@GMATPrepNow posted a reply to A box of balls originally contained 2 blue balls for every in the Problem Solving forum
“We can also solve by using 2 variables... Let R = the ORIGINAL number of red balls in the box Let B = the ORIGINAL number of blue balls in the box A box of balls originally contained 2 blue balls for every red ball. In other words, the ratio of red balls to blue balls is 1/2 (aka 1 : 2) ...”
August 2, 2018
Brent@GMATPrepNow posted a reply to Is 0 between x and y? in the Data Sufficiency forum
“Target question: Is 0 between x and y? 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 = 2 and y = -1. In this case, the answer to the target question is YES, ...”
August 2, 2018
Brent@GMATPrepNow posted a reply to If n = (x^5)*(y^7), where x and y are positive integers in the Data Sufficiency forum
“Statement 1 tells us that x and y are primes, but it doesn''t tell us that x and y are DIFFERENT primes. So, for example, if x = y = 2, then n = (2^5)(2^7) = 2^12, and 2^12 has 13 positive divisors. Conversely, if x = 2 and y = 3, then n = (2^5)(3^7), which has 48 positive divisors. So, ...”
August 2, 2018
Brent@GMATPrepNow posted a reply to if product X costs 15000 and product Y costs 27000 in the Problem Solving forum
“Are you sure you transcribed the question correctly? As it stands, it''s not answerable. Cheers, Brent”
August 2, 2018
Brent@GMATPrepNow posted a reply to If (n+2)!/n!=90, then n=? in the Problem Solving forum
“(n+2)! = (n+2)(n+1)(n)(n-1)(n-2)....(3)(2)(1) n! = (n)(n-1)(n-2)....(3)(2)(1) Given: (n+2)!/n! = 90 Rewrite as: (n+2)(n+1)(n)(n-1)(n-2)....(3)(2)(1)/(n)(n-1)(n-2)....(3)(2)(1) = 90 Simplify: (n+2)(n+1) = 90 At this point, we can simply test the answer choices. A) n = 8 Take (n+2)(n+1) = ...”
August 2, 2018
Brent@GMATPrepNow posted a reply to If x + 2 = (x + 11)/(x + 3) then x^2 + 4x - 5 = in the Problem Solving forum
“Given: x + 2 = (x + 11)/(x + 3) Multiply both sides by (x+3) to get: (x + 2)(x + 3) = (x + 11) Expand and simplify: x² + 5x + 6 = x + 11 Subtract x from both sides to get: x² + 4x + 6 = 11 Subtract 11 from both sides to get: x² + 4x - 5 = 0 Answer: C Cheers, Brent”
August 2, 2018
Brent@GMATPrepNow posted a reply to If 3 years ago Jennifer was 22 years old, how old is Carmen in the Data Sufficiency forum
“Target question: How old is Carmen now? Given: 3 years ago Jennifer was 22 years old So, Jennifer''s PRESENT age is 25 Statement 1: 10 years ago, Carmen was twice as old as Jennifer. If Jennifer''s PRESENT age is 25, then Jennifer''s age 10 YEARS AGO was 15 This means Carmen''s age 10 ...”
August 2, 2018
GMATGuruNY posted a reply to speed and distance in the Data Sufficiency forum
“Regular day: Let r = the regular rate and t = the regular time, implying that the distance to the office = rt. Last Wednesday: Since Mr. David drives 25% faster -- 5/4 of his regular speed -- the rate = (5/4)r. Since Mr. David leaves 30 minutes late -- reducing the time by 30 minutes -- the ...”
August 2, 2018
Brent@GMATPrepNow posted a reply to A rope 40 feet long is cut into two pieces. If one piece is in the Problem Solving forum
“We can also test the answer choices Start with the middle answer choice C C) 18 If the shorter piece is 18 feet long, then the longer piece is 36 feet long Sum of lengths = 18 + 36 = 54 NO GOOD. We want a sum of 40 feet (as per the question) So, we can ELIMINATE C. Also, since we need ...”
August 2, 2018
Brent@GMATPrepNow posted a reply to numbers in the Data Sufficiency forum
“ Given: x = y/7 Target question: Is x < 30? This is a good candidate for rephrasing the target question. Since x = y/7, we can replace x with y/7 to get... REPHRASED target question: Is y/7 < 30? Let''s rephrase the target question even more.... Take: y/7 < 30 Multiply both ...”
August 2, 2018
Brent@GMATPrepNow posted a reply to Challenge question: In the x-y coordinate plane, lines J in the Problem Solving forum
“Key Concepts: point B lies on line K, and point C lies on line K Since both points lie on line K, the slope between points B and C will be the same as the slope of line K. To find the slope of line K, let''s take the equation of line K (6y + 3x = -2), and rewrite it in slope y-intercept form (y ...”
August 1, 2018
GMATGuruNY posted a reply to sets in the Problem Solving forum
“To organize the data, use a DOUBLE-MATRIX. 10% of the people do not have a university diploma but have a job of their choice. The following matrix is yielded: https://s33.postimg.cc/ouzby26ln/matrix_diploma_job_1.png 40% people have a job of their choice. The following matrix is yielded: ...”
August 1, 2018
GMATGuruNY posted a reply to Speed/time in the Problem Solving forum
“Since Deb drives for 3/4 of an hour at a rate of 40 mph, the driving distance to work = rt = (40)(3/4) = 30 miles. Since the biking distance is 20% less than the driving distance, the biking distance = 30 - (1/5)(30) = 24 miles. To guarantee an on-time arrival at even the least possible biking ...”
August 1, 2018
GMATGuruNY posted a reply to Mr. Alex usually starts at 9:00am and reaches his office in the Data Sufficiency forum
“20t feet. Statement 1: Since Mr. Alex leaves 20 minutes early last Monday -- giving himself an additional 20 minutes -- the time last Monday = t + 20 minutes. Since Mr. Alex drives 20% slower, the rate last Monday = 20 - (20% of 20) = 16 feet per minute. Thus, the distance traveled last Monday ...”
July 31, 2018
GMATGuruNY posted a reply to What is the median of 10 numbers? in the Data Sufficiency forum
“Statement 1: Case 1: X, X, X, X, 10, 10, X, X, X, X Here, the 6 blue values are all less than or equal to 10. In this case, the median = (10+10)/2 = 10 Case 2: X, X, X, X, 8, 10, X, X, X, X Here, the 6 red values are all less than or equal to 10. In this case, the median = (8+10)/2 = 9. Since ...”
July 31, 2018
GMATGuruNY posted a reply to George and Steven drive separate cars the same distance from in the Data Sufficiency forum
“Statement 1: Here, Steven''s time can be any nonnegative value. INSUFFICIENT. Statement 2: Rate and time have a RECIPROCAL RELATIONSHIP. Since George''s speed in 2/3 Steven''s speed, George''s time is 3/2 Steven''s time. Since George''s time is 3.5 hours, we get: 3.5 = (3/2)t 7 = 3t 7/3 = ...”
July 30, 2018
Brent@GMATPrepNow posted a new topic called Challenge question: In the x-y coordinate plane, lines J in the Problem Solving forum
“Line J: 4x - 7 = 6y Line K: 6y + 3x = -2 Line L: 2x = 5 - y In the x-y coordinate plane, lines J, K and L are defined by the above equations. Point B is the point of intersection of lines J and K. Point C is the point of intersection of lines K and L. What is the slope of line segment BC? ...”
July 30, 2018
GMATGuruNY posted a reply to If m=-1 and n = 1^2 + 2^2 + … + 10^2, what is the value of in the Problem Solving forum
“(-1)^odd = -1. (-1)^even = 1. The exponents for the expression in blue are 4 consecutive integers -- n, n+1, n+2, n+3 -- implying that two of the exponents will be ODD, while the other two will be EVEN. Thus, two of the terms in the blue expression must be equal to -1, while the other two must be ...”
July 30, 2018
GMATGuruNY posted a reply to A box of balls originally contained 2 blue balls for every in the Problem Solving forum
“A box of balls originally contained 2 blue balls for every red ball. Let the number of red balls = x and the number blue balls = 2x, implying that the total number of balls = x+2x = 3x. After 12 red balls were added to the box, the ratio of red balls to blue balls became 5 to 2. Since 12 red ...”
July 30, 2018
GMATGuruNY posted a reply to What is the probability of getting only 1 head in a single in the Problem Solving forum
“P(HTT) = 1/2 * 1/2 * 1/2 = 1/8. Since a good outcome will be yielded if H is first, second or third, we multiply by 3: 1/8 * 3 = 3/8. The correct answer is B.”
July 30, 2018
Brent@GMATPrepNow posted a reply to GMATPrep Practice Exam #1 - What Does my Percentile Mean? in the GMAT Math forum
“A 28-point percentile increase is no small matter. Day 42 is the last day that you learn new content, and the remaining days are devoted to taking practice tests and working on weaknesses. So, you can work on further improving your quant score during that time. Cheers, Brent”
July 29, 2018
GMATGuruNY posted a reply to Let abcd be a general four-digit number. How many odd four in the Problem Solving forum
“Condition: a*b = integer cd Since abcd must be odd and composed of 4 distinct digits, we get the following options for integer cd: 21, 31, 41, 51, 61, 71, 81, 91 13, 23, 43, 53, 63, 73, 83, 93 15, 25, 35, 45, 65, 75, 85, 95 17, 27, 37, 47, 57, 67, 87, 97 19, 29, 39, 49, 59, 69, 79, 89 ...”
July 29, 2018
GMATGuruNY posted a reply to Two thirds of the roads from A to B are at least 5 miles in the Problem Solving forum
“P(at least one of the 2 selected roads is at least 5 miles long) = 1 - P(neither of the 2 selected roads is at least 5 miles long) From A to B: Since 2/3 of the roads are at least 5 miles long, 1/3 are not. Thus, the probability of selecting a road that is not at least 5 miles long = 1/3. ...”
July 29, 2018
GMATGuruNY posted a reply to If s is the sum of all integers from 1 to 30, inclusive, in the Problem Solving forum
“To calculate the sum of an integer''s positive factors: 1. Prime-factorize the integer 2. Write the prime-factorization in the form (a^p)(b^q)(c^r)... 3. Sum of the factors = (1+a¹+ a²+a³+...+a^p)(1+b¹+ b²+b³+...+b^q)(1+c¹+ c²+c³+...+c^r)... What is the sum of the positive factors of ...”
July 29, 2018
GMATGuruNY posted a reply to In 1990 850 million movie tickets were sold in the United St in the Data Sufficiency forum
“The statement in red does not accurately reflect the information in Statement 2. Statement 2: People under the age of 20 spent $2.2 billion MORE on movie tickets than did people over the age of 50. Here, the total amount spent by people under the age of 20 ≠ $2.2 billion. The usage of MORE ...”
July 28, 2018
GMATGuruNY posted a reply to If a sequence of positive odd integers has six terms contain in the Problem Solving forum
“This problem is invalid. Since the only conditions are that six terms must be positive and odd and have a total of 13 digits, an infinite number of cases are possible. Here are two options: 11, 13, 15, 17, 19, 101 13, 11, 15, 17, 19, 101 Since the sequence does not have to be ascending, any of ...”
July 28, 2018
GMATGuruNY posted a reply to If the sum of 3 consecutive integers is 54, then what is the in the Problem Solving forum
“Average of the 3 consecutive integers = sum/quantity = 54/3 = 18. For any set of consecutive integers, average = median. Thus, the median of the 3 integers = 18, implying that the 3 integers are 17, 18, and 19. Product of the smallest and largest = 17*19 = integer with a units digit of 3. The ...”
July 28, 2018
GMATGuruNY posted a reply to What is the sum of the digits of two-digit positive integer in the Data Sufficiency forum
“Statement 1: Let M = 10T + U, where T = the tens digit and U = the units digit. When the digits are reversed, we get: 10U + T. Since the reversed integer is 27 more than M, we get: (10U + T) - (10T + U) = 27 9U - 9T = 27 9(U-T) = 27 U-T = 3. U = T+3 The resulting equation indicates ...”
July 28, 2018
GMATGuruNY posted a reply to During a 40-mile trip, Marla traveled at an average speed of in the Data Sufficiency forum
“Time and rate are RECIPROCALS. x = the REGULAR speed. 1.25x = the FASTER speed. 1.25x = (125/100)x = (5/4)x. 5/4 the rate implies 4/5 the time. Thus: The time needed at the FASTER speed is equal to 4/5 the time needed at the REGULAR speed. The question stems asks for the following ratio: ...”
July 28, 2018
beatthegmat posted a reply to GMAT OG 2019 Because many of Australia’s marsupials, in the Sentence Correction forum
“Entered OA has been corrected to E”
July 27, 2018
July 27, 2018
GMATGuruNY posted a reply to A jar contains 12 marbles consisting of an equal number of in the Problem Solving forum
“For only 2 colors to remain after 4 marbles have been removed, the 4 selected marbles must be of the same color. The first selected marble can be of ANY COLOR. A good outcome will be yielded if the second, third and fourth marbles are of the SAME COLOR as the first. P(2nd marble is of the same ...”
July 27, 2018
Brent@GMATPrepNow posted a reply to Challenge question: Which of the following is NOT a root... in the Problem Solving forum
“APPROACH 1: Plug in each answer choice to see which value does NOT satisfy the equation (slow but...) For example, C) x = 3 We get: (3² + 3 - 20)² - 2(3² + 3 - 20) - 63 = 17 Evaluate: (-8)² - 2(-8) - 63 = 17 Simplify: 64 - 16 - 63 = 17 Works! So, x = 3 is a valid solution Try D) x = 4 ...”
July 27, 2018
Brent@GMATPrepNow posted a reply to Is x a positive number? in the Data Sufficiency forum
“Target question: Is x a positive number? Statement 1: (x – 2)^2 > 2 Let''s TEST some values. There are several values of x that satisfy statement 1. Here are two: Case a: x = 4 works, since (4 – 2)^2 > 2. In this case, the answer to the target question is YES, x is positive Case ...”
July 27, 2018
GMATGuruNY posted a reply to After t seconds, the height of a ball from the ground is giv in the Data Sufficiency forum
“f(x) = ax² + bx + c is the equation of a parabola. If a<0, then the parabola opens DOWNWARD, with a maximum value when: $$x\ =\ \frac{-b}{2a}$$ Given quadratic: h = -9.8t² + ft + g. Here, the maximum height will be yielded when: $$t\ =\ \frac{-f}{\left(2\right)\left(-9.8\right)}$$ ...”
July 27, 2018
GMATGuruNY posted a reply to If the length of each edge of a certain rectangular solid is in the Data Sufficiency forum
“For the solid to have four faces with the same dimensions, two opposing faces must be SQUARES, as in the following figure:https://preview.ibb.co/koZpb8/rectangular_solid_with_square_base.png In the figure above: The area of the square base and the area of the square top = L*L. The areas of the ...”
July 27, 2018
Brent@GMATPrepNow posted a reply to Pears in the Data Sufficiency forum
“ Given: Pat bought 5 pounds of apples. Target question: How many pounds of pears could Pat have bought for the same amount of money? This is a good candidate for rephrasing the target question. Let A = the price per pound of apples Let P = the price per pound of pears If Pat bought 5 ...”
July 26, 2018
GMATGuruNY posted a reply to Al, Pablo and Marsha shared the driving on a 1,500-mile trip in the Data Sufficiency forum
“Statement 1: No info about Martha. INSUFFICIENT. Statement 2: Distance traveled by Martha = rt = 50*9 = 450 miles. Remaining distance traveled by Al and Pablo = 1500 - 450 = 1050 miles. Case 1: Al''s distance = 1000 miles, Pablo''s distance = 50 miles In this case, Al drives the greatest ...”
July 26, 2018
Brent@GMATPrepNow posted a reply to Challenge Question: the two lines are tangent to the circle in the Problem Solving forum
“If AC = 10, then BC = 10 https://i.imgur.com/43RWU7u.png Since ABC is an isosceles triangle, the following gray line will create two right triangles... https://i.imgur.com/VqAmtBP.png Now focus on the following blue triangle. Its measurements have a lot in common with the BASE 30-60-90 ...”
July 26, 2018
Brent@GMATPrepNow posted a reply to What is the remainder when 7^8 is divided by 100? in the Problem Solving forum
“Let''s examine 7^8 - 1 Why would I do this? Well, I know that 7^2 + 1 = 50, which is a factor of 100. So, perhaps it''s the case that 7^8 - 1 is divisible by 100, in which case 7^8 will leave a remainder of 1 when divided by 100 7^8 - 1 is a difference of squares. So, 7^8 - 1 = (7^4 + ...”
July 26, 2018
GMATGuruNY posted a reply to What is the remainder when 7^8 is divided by 100? in the Problem Solving forum
“When an integer is divided by 100, the remainder will have the same units digit as the integer. Thus, to determine which answer choice represents the remainder when 7⁸ is divided by 100, we need to know the units digit of 7⁸. When an integer is raised to consecutive powers, the resulting units ...”
July 26, 2018
GMATGuruNY posted a reply to John and Ed work for the same Sales Company. John receives a in the Problem Solving forum
“We can PLUG IN THE ANSWERS, which represent the amount of profit. Since Ed earns a flat salary of $1000 if the amount of profit does not exceed $8000 -- and all of the answer choices are less than 8000 -- Ed''s earnings = $1000. Since John and Ed must earn the same amount, John must also earn ...”
July 26, 2018
GMATGuruNY posted a reply to In how many ways can 6 chocolates be distributed among 3 in the Problem Solving forum
“We can apply the SEPARATOR METHOD, which I describe here: https://www.beatthegmat.com/combinations-t120668.html To solve the problem above, we need 6 identical chocolates and 2 identical separators, as follows: OO|OO|OO. The number of ways to arrange 8 elements composed of 6 identical ...”
July 26, 2018
beatthegmat started following dnhgmat77
July 26, 2018
GMATGuruNY posted a reply to Please explain in the Sentence Correction forum
“This line of reasoning applies to a VERBing modifier preceded by CLAUSE + COMMA. In C, making is preceded not by CLAUSE + COMMA but by a NOUN PHRASE (a part of a deal). The referent for this noun phrase is unclear, as discussed in my earlier post. As a result, a reader cannot be sure whether ...”
July 25, 2018
GMATGuruNY posted a reply to For integers x and y, 25^(−10)*100^x=2^y. What is the valu in the Problem Solving forum
“25¯¹⁰ * 100^x = 2^y 1/25¹⁰ * (25*4)^x= 2^y (1/25¹⁰)(25^x)(4^x) = 2^y In the resulting blue equation, x and y will be integers if x=10, with the result that (25^x)/25¹⁰ = 1. Substituting x=10 into the blue equation, we get: (25¹⁰/25¹⁰) * 4¹⁰ = 2^y 4¹⁰ = ...”
July 25, 2018
GMATGuruNY posted a reply to CEO in the Sentence Correction forum
“C: CEOs now earn 419 times the pay of blue-collar workers, as compared to 42 times their pay. Because the two blue portions are parallel, their pay clearly refers to the pay of blue-collar workers.”
July 25, 2018
GMATGuruNY posted a reply to CEO in the Sentence Correction forum
“The construction in red is acceptable when it serves to express how a subject CHANGES. An OA in the OG for Verbal: Its numbers are now five times greater than when the use of DDT was sharply restricted in the early 1970. Here, the portion in blue serves to express how ITS NUMBERS have changed ...”
July 25, 2018
Brent@GMATPrepNow posted a reply to If a solid metal cylinder with radius 3 and height 12 is mel in the Problem Solving forum
“Key concept: the volume of the cylinder = the volume of the sphere volume of the cylinder = πr²h = π(3²)(12) = 108π So, the volume of the sphere = 108π Volume of sphere = (4/3)(π)(radius³) So, (4/3)(π)(radius³) = 108π Divide both sides by π to get: (4/3)(radius³) = 108 ...”
July 25, 2018
Brent@GMATPrepNow posted a new topic called Challenge question: Which of the following is NOT a root... in the Problem Solving forum
“Which of the following is NOT a root of the equation (x² + x - 20)² - 2(x² + x - 20) - 63 = 17 A) -6 B) -4 C) 3 D) 4 E) 5 Answer: D Difficulty level: 600 – 650 Source: www.gmatprepnow.com *Note: there are at least 3 different solutions possible”
July 25, 2018
Brent@GMATPrepNow posted a reply to If x and y are greater than 0, is x = 1 ? in the Data Sufficiency forum
“Target question: Is x = 1 ? Given: x and y are POSITIVE Statement 1: x/y = 1 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 = 1. In this case, the answer to the target question is YES, x DOES equal 1 Case b: ...”
July 25, 2018
Brent@GMATPrepNow posted a reply to 60 Day Study Guide: Missing Days in the The 60-Day GMAT Study Guide forum
“Sorry, but BTG won''t do that. Cheers, Brent”
July 25, 2018
Brent@GMATPrepNow posted a reply to A bus trip of 450 miles would have taken 1 hour less if the in the Problem Solving forum
“Let''s start with a word equation: travel time at actual speed = travel time at faster speed + 1 hour In other words: travel time at S mph = travel time at (S + 5) mph + 1 hour travel time = distance/speed So, we get: 450/S= 450/(S + 5) + 1 Multiply both sides by S to get: 450 = 450S/(S+5) + ...”
July 25, 2018
GMATGuruNY posted a reply to If p is a prime number and n is a positive integer, what is in the Data Sufficiency forum
“To count the factors of a positive integer: 1. Prime-factorize the integer 2. Write the prime-factorization in the form Statement 1: Test one case that also satisfies Statement 2. Case 1: p=5, with the result that (3^n)(p^2) = 3⁴5² Adding 1 to each exponent and multiplying, we get: Number ...”
July 25, 2018
GMATGuruNY posted a reply to If x and y are integers such that (xy)^2 + x^2 – 2xy – 2 in the Problem Solving forum
“We can PLUG IN THE ANSWERS, which represent the value of y. B: y=-1 Substituting y=-1 into (xy)² + x² – 2xy – 2x + 2 = 0, we get: x² + x² + 2x – 2x + 2 = 0 2x² + 2 = 0 x² + 1 = 0 x² = -1 Since the square of a value cannot be negative, eliminate B. D: y=1 Substituting y=1 ...”
July 25, 2018
GMATGuruNY posted a reply to A bus trip of 450 miles would have taken 1 hour less if the in the Problem Solving forum
“Since the time difference yielded by the two speeds is an INTEGER -- 1 hour less -- the actual speed and hypothetical greater speed must both divide evenly into the 450-mile distance. We can PLUG IN THE ANSWERS, which represent the actual speed. Since A, B and E do not evenly into 450, eliminate ...”
July 25, 2018
GMATGuruNY posted a reply to Is the United States Singular or plural? in the Sentence Correction forum
“Correct.”
July 25, 2018
Brent@GMATPrepNow posted a reply to Moe is 20% taller than Jane. If Moe is x inches tall, which in the Problem Solving forum
“I created this question to highlight a common misconception that goes something like this: If Moe is 20% taller then Jane, then Jane must be 20% shorter than Moe. If you have this misconception, then you will incorrectly choose A as your answer. For more on this common misconception, read ...”
July 24, 2018
Brent@GMATPrepNow posted a reply to OG Quant Review - PS - Q 103 in the Problem Solving forum
“Given: x³ - x = (x - a)(x - b)(x - c) Factor x from left side: x(x² - 1) = (x - a)(x - b)(x - c) x² - 1 is a difference of squares, so we can factor that: x(x + 1)(x - 1) = (x - a)(x - b)(x - c) Rewrite first 2 terms as: (x - 0)(x - -1)(x - 1) = (x - a)(x - b)(x - c) Rearrange as: (x - 1)(x - ...”
July 24, 2018
GMATGuruNY posted a reply to During a 6-day local trade show, the least number of people in the Data Sufficiency forum
“Statement 1: Average for 4 of the 6 days = 100 per day. Least possible average for the other 2 days = 80 per day. Since there are MORE DAYS with an average of 100 per day than with an average of at least 80 per day, the average for all 6 days must be CLOSER TO 100 THAN TO 80. Thus, the average ...”
July 24, 2018
GMATGuruNY posted a reply to Each week a certain salesman is paid a fixed amount equal to in the Data Sufficiency forum
“One way to evaluate Statement 1 is to test whether the value given in Statement 2 -- $5000 in sales -- is the ONLY value that will also satisfy Statement 1. Statement 1: The total amount the salesman was paid last week is equal to 10 percent of the amount of his sales last week. Case 1: Let ...”
July 24, 2018
Brent@GMATPrepNow posted a new topic called Challenge Question: the two lines are tangent to the circle in the Problem Solving forum
“https://i.imgur.com/c9biFrc.png The two lines are tangent to the circle. If AC = 10 and AB = 10√3, what is the area of the circle? A) 100π B) 150π C) 200π D) 250π E) 300π Answer: E Difficulty level: 650 - 700 Source: www.gmatprepnow.com *I''ll post a solution in 2 days”
July 24, 2018
GMATGuruNY posted a reply to Machines X and Y produced identical bottles at different in the Data Sufficiency forum
“Statement 1: X produced 30 bottles per minute. Thus, the work produced by X in 240 minutes = r*t = 30*240. No information about how much work was produced by Y. INSUFFICIENT. Statement 2: Machine X produced twice as many bottles in 4 hours as Machine Y produced in 3 hours. Thus, for ...”
July 24, 2018
GMATGuruNY posted a reply to Is xy > 0 ? in the Data Sufficiency forum
“Statement 1: x > y-2 If y=2 and x= 1, is 1*2 > 0? Yes. If y= -1 and x = 1, is 1*(-1) > 0? No. Since the answer is YES in the first case but NO in the second case, INSUFFICIENT. Statement 2: x < 2y-6 If y=1 and x = -10, is 1*(-10) > 0? No. If y = 10 and x = 1, is 1*10 > ...”
July 24, 2018
GMATGuruNY posted a reply to There are 3 ways to make the number 12 using products of two in the Problem Solving forum
“To count the factors of a positive integer: 1. Prime-factorize the integer 2. Write the prime-factorization in the form (a^p)(b^q)(c^r)... 3. The number of factors = (p+1)(q+1)(r+1).. 2700 = 2²3³5² Adding 1 to each exponent and multiplying, we get: Total number of factors = ...”
July 24, 2018
beatthegmat started following nychivas
July 24, 2018
GMATGuruNY posted a reply to Number Systems -Sequence and Series in the Problem Solving forum
“Good catch! I''ve corrected the typo.”
July 24, 2018
Brent@GMATPrepNow posted a new topic called If a solid metal cylinder with radius 3 and height 12 is mel in the Problem Solving forum
“If a solid metal cylinder with radius 3 and height 12 is melted and then formed into a solid sphere, what is the radius of the sphere? Note: Volume of sphere = (4/3)(π)(radius³) A) ∛6 B) ∛12 C) ∛36 D) 3 E) 3∛3 Answer: E Difficulty level: 600 - 650 Source: www.gmatprepnow.com ...”
July 23, 2018
Brent@GMATPrepNow posted a reply to Is 1/x>1/y? in the Data Sufficiency forum
“Target question: Is 1/x > 1/y? This is a good candidate for rephrasing the target question. Take: 1/x > 1/y Subtract 1/y from both sides to get: 1/x - 1/y > 0 Rewrite with common denominators: y/xy - x/xy > 0 Combine: (y - x)/xy > 0 REPHRASED target question: Is (y - ...”
July 23, 2018
Brent@GMATPrepNow posted a reply to If john makes a contribution to a charity fund at school in the Problem Solving forum
“Mitch''s approach is the most straightforward. However, here''s an algebraic version: Let J = the John''s donation Let a, b, c, d and e = the donations of the other 5 donors. John makes a contribution to a charity fund at school, the average contribution size will increase by 50% reaching $75 ...”
July 23, 2018
GMATGuruNY posted a reply to If john makes a contribution to a charity fund at school in the Problem Solving forum
“Since $75 is 50% more than $50, the first 5 contributions were worth an average of $50. Thus, the sum of the first 5 contributions = 5*50 = 250. Since the average of all 6 contributions = $75, the sum of all 6 contributions = 6*75 = 450. Thus, John''s contribution = (sum of all 6 contributions) - ...”
July 23, 2018
GMATGuruNY posted a reply to How many positive integers less than 28 are prime numbers, in the Problem Solving forum
“Any even integer other than 2 and 4 can be expressed as the sum of a positive multiple of 2 and a positive multiple of 4, yielding the following options less than 28: 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26 --> 11 options. Prime numbers less than 28: 2, 3, 5, 7, 11, 13, 17, 19, 23 --> 9 ...”
July 23, 2018
GMATGuruNY posted a reply to If m is a two-digit number, what is the remainder when m is in the Data Sufficiency forum
“Statement 1: Make a list of options for m+1: m+1 = 12, 15, 18, 21, 24, 27... To get a list option for m, subtract 1 from every value in the list above: m = 11, 14, 17, 20, 23, 26... When any value in the resulting list is divided by 3, the remainder in every case is 2. SUFFICIENT. Statement ...”
July 23, 2018
GMATGuruNY posted a reply to A credit card company has a cash back option for their in the Problem Solving forum
“(1.5% of 5000) + (2.5% of 5000) = 75 + 125 = 200. We can PLUG IN THE ANSWERS, which represent the total annual charge. When the correct answer is plugged in, the cash back will be 2.6% of the total annual charge. D: 26,000 Since 3% is earned on the amount over $10,000 -- in other words, since ...”
July 23, 2018
Brent@GMATPrepNow posted a new topic called Moe is 20% taller than Jane. If Moe is x inches tall, which in the Problem Solving forum
“Moe is 20% taller than Jane. If Moe is x inches tall, which of the following represents Jane''s height in inches? A) 4x/5 B) 5x/6 C) 2x/3 D) 5x/4 E) 6x/5 Answer: B Difficulty level: 550 - 600 Source: www.gmatprepnow.com *I''ll post a solution in 2 days”
July 22, 2018
Brent@GMATPrepNow posted a reply to If there are fewer than 8 zeroes in the Problem Solving forum
“First: (t/1000)^4 = (t^4)/(1000^4) Now recognize that 1000^4 = (10^3)^4 = 10^12 So, (t/1000)^4 = (t^4)/(1000^4) = (t^4)/(10^12) IMPORTANT: When we divide a number by 10^12, we must move the decimal point 12 spaces to the left So, for example, 1234567/10^12 = 0.000001234567 Likewise, ...”
July 22, 2018
GMATGuruNY posted a reply to The ratio of spinsters to cats is 2 to 7. If there are 25 in the Problem Solving forum
“Given ratio = S:C = 2:7. The difference between the parts of the ratio = 7-2 = 5. Since the actual difference between the number of cats and the number of spinsters is five times as great -- 25 -- each part of the ratio must be multiplied by a FACTOR OF 5: S:C = (2*5) : (7*5) = 10:35, with the ...”
July 22, 2018
GMATGuruNY posted a reply to At the start of the day the amount of water in two identical in the Problem Solving forum
“Since the resulting ratio = A:B = 3:10, and all of the values in the problem are integers, the correct answer must yield a multiple of 10 when added to the 2 original liters in B. Only D is viable: 48+2 = 50 liters. The correct answer is D.”
July 22, 2018
GMATGuruNY posted a reply to An airplane was due north of a tropical island when in the Data Sufficiency forum
“Statements combined: https://preview.ibb.co/i0YOtd/plane.png The dotted green line indicates the plane''s position at 12pm. The blue right triangle indicates the plane''s position at 3pm. The two dotted red lines show positions for the island that are 450 miles from the plane''s position at ...”
July 22, 2018
GMATGuruNY posted a reply to Is the average age of a class of 60 students more than 30 in the Data Sufficiency forum
“If the average age of the students is exactly 30, then the sum of the 60 ages = 60*30 = 1800. Implication: For the average age to be GREATER THAN 30, the SUM of the 60 ages must be GREATER THAN 1800. Question stem, rephrased: Is the sum of the 60 ages greater than 1800? Statement 1: Since ...”
July 22, 2018
GMATGuruNY posted a reply to Each day a man meets his wife at the train station after in the Problem Solving forum
“Normal day: 4pm --> The wife leaves home and drives to the station. 5pm --> The husband''s train and the wife both arrive at the station. 6pm --> The husband and wife arrive home. Implication: The normal driving time in each direction = 60 minutes. Today: Since the wife and the ...”
July 21, 2018
Brent@GMATPrepNow posted a reply to At least 100 students at a certain high school study in the Data Sufficiency forum
“We can use the Double Matrix method. It 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: - studies Japanese or does NOT ...”
July 20, 2018
GMATGuruNY posted a reply to In how many different ways can a group of twelve people be in the Problem Solving forum
“Since there are 12 people, the first person selected can be paired with any of the 11 other people, yielding 11 POSSIBLE PAIRS. Since 2 of the 12 people have been selected thus far, the number of people remaining = 12-2 = 10. Since 10 people remain, the next person selected can be paired with ...”
July 20, 2018
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