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 = ...”
Today
Brent@GMATPrepNow posted a reply to If xy ≠ 0 and x^2+4y^2=4xy, (x+y)/(x-y)=? in the Problem Solving forum
“GIVEN: x² + 4y² = 4xy Subtract 4xy from both sides to get: x² - 4xy + 4y² = 0 Factor left side to get: (x - 2y)(x - 2y) = 0 So, we can conclude that (x - 2y) = 0, which means x = 2y Now take (x+y)/(x-y) and replace x with 2y to get: (x + y)/(x - y) = (2y + y)/(2y - y) = 3y/y = 3 ...”
Today
Brent@GMATPrepNow posted a reply to OG #217 question in the Problem Solving forum
“P(selecting a sibling pair) = P(select a junior with a sibling AND select the senior who is that junior''s sibling) = P(select a junior with a sibling) x P(select the senior who is that junior''s siblingx 1/800 = 60/800,000 = 3/40,000 = A Note: P(select a junior with a sibling) = 60/1000, ...”
Yesterday
Brent@GMATPrepNow posted a reply to In the figure AB and CD are two diameters of circle. in the Problem Solving forum
“Let''s use some useful circle properties First let''s add a blue line, to divide ∠CEB into 2 angles https://i.imgur.com/xe05QIU.png CD is the DIAMETER of the circle Since ∠CED is an inscribed angle containing (aka "holding") the diameter, we can conclude that ∠CED = 90° ...”
Yesterday
Brent@GMATPrepNow posted a reply to Is the tallest child in Class A taller than tallest child in in the Data Sufficiency forum
“Target question: Is the tallest child in Class A is taller than tallest child in Class B? Jump to . . . Statements 1 and 2 COMBINED There are several scenarios that satisfy BOTH statements. Here are two: Case a: Class A heights = {1, 50} and Class B heights = {2, 40}. In this case, the ...”
Yesterday
Brent@GMATPrepNow posted a reply to Eight women and two men are available to serve on a in the Problem Solving forum
“When it comes to probability questions involving "at least," it''s best to try using the complement. That is, P(Event A happening) = 1 - P(Event A not happening) So, here we get: P(getting at least 1 man) = 1 - P(not getting at least 1 man) What does it mean to not get at least 1 man? ...”
November 11, 2018
Brent@GMATPrepNow posted a reply to If the positive integer n is greater than 6, what is the in the Data Sufficiency forum
“Here''s a somewhat long approach (but it works!): Target question: What is the remainder when n is divided by 6? Given: Positive integer n is greater than 6 Statement 1: When n is divided by 9, the remainder is 2. ------ASIDE---------------- When it comes to remainders, we have a ...”
November 11, 2018
Brent@GMATPrepNow posted a reply to If x and y are positive integers, what is the remainder when in the Data Sufficiency forum
“Hi Swerve, To avoid ambiguity, you might want to add some spaces or brackets to the original expression. As it stands, 10^x+y could be interpreted as either 10^(x+y) or (10^x) + y Cheers, Brent”
November 11, 2018
Brent@GMATPrepNow posted a reply to If x and y are positive integers such that x = 8y + 12, what in the Data Sufficiency forum
“Target question: What is the greatest common divisor of x and y? Given: x = 8y + 12 Statement 1: x = 12u, where u is an integer. There are several pairs of values that satisfy the given conditions. Here are two: Case a: x=36 and y=3, in which case the GCD of x and y is 3 Case b: x=60 ...”
November 11, 2018
Brent@GMATPrepNow posted a reply to Which of the following is closest to the value of (2^23) in the Problem Solving forum
“(2^23)(5^26) = (2^23)(5^23)(5^3) = (2^23)(5^23)(5^3) = (10^23)(5^3) = (10^23)(125) ≈ (10^23)(100) ≈(10^23)(10^2) ≈10^25 Answer: C Cheers, Brent”
November 11, 2018
Brent@GMATPrepNow posted a reply to A gardener is going to plant 2 red rosebushes and 2 white in the Problem Solving forum
“We can also apply probability rules: P(2 middle bushes are red) = P(1st bush is white AND 2nd bush is red AND 3rd bush is red AND 4th bush is white) = P(1st bush is white) x P(2nd bush is red) x P(3rd bush is red) x P(4th bush is white) = 2/4 x 2/3 x 1/2 x 1/1 = 1/6 = B Cheers, Brent”
November 11, 2018
Brent@GMATPrepNow posted a reply to A gardener is going to plant 2 red rosebushes and 2 white in the Problem Solving forum
“As with many probability questions, we can also solve this using counting techniques. P(2 middle are red) = (# of outcomes with 2 red in middle)/(total number of outcomes) Label the 4 bushes as W1, W2, R1, R2 total number of outcomes We have 4 plants, so we can arrange them in 4! ways = ...”
November 11, 2018
Brent@GMATPrepNow posted a reply to Of the first three dozen cookies baked at a bake shop on a in the Data Sufficiency forum
“ Given: Of the first three dozen (36) cookies baked at a bake shop on a certain day, 1/3 were chocolate chip cookies. 1/2 of the remaining cookies that were baked that day were chocolate chip cookies, 1/3 of 36 = 12. So, 12 chocolate cookies were baked in the first round of baking. Let x = ...”
November 10, 2018
Brent@GMATPrepNow posted a reply to There were 36,000 hardback copies of a certain novel sold in the Problem Solving forum
“From the time the first paperback copy was sold until the last copy of the novel was sold 9 times as many paperback copies as hardback copies were sold Let x = number of hardback copies sold during this time So 9x = number of paperback copies sold during this time So, x + 9x = total number of ...”
November 10, 2018
Brent@GMATPrepNow posted a reply to A box contains 10 balls numbered from 1 to 10 inclusive. If in the Problem Solving forum
“P(Ann and Jane remove same ball) = P(Ann removes ANY ball AND Jane''s ball matches Ann''s ball) = P(Ann removes ANY ball) x P(Jane''s ball matches Ann''s ball) = 1 x 1/10 = 1/10 Answer: D Aside: Once Jane removes her ball (and then replaces it), we have 10 balls, and 1 of them is the one ...”
November 10, 2018
Brent@GMATPrepNow posted a reply to If CD = 6, what is the length of BC? in the Data Sufficiency forum
“Is there an image? Cheers, Brent”
November 9, 2018
Brent@GMATPrepNow posted a reply to Andrew has a certain number of coins in his pocket. He has in the Problem Solving forum
“Let x = number of QUARTERS in pocket So, 0.25x = VALUE of quarters in pocket He has three times as many dimes as quarters So, 3x = number of DIMES in pocket So, 0.10(3x) = 0.3x = VALUE of dimes in pocket He has six times as many nickels as dimes. So, (6)(3x) = number of NICKELS in ...”
November 8, 2018
Brent@GMATPrepNow posted a reply to Challenge: Al, Bob, Cal and Don each own 1 hat. If the 4... in the Problem Solving forum
“I created this question to highlight many students'' tendency to avoid listing and counting as a possible approach. As you''ll see, the approach is probably the fastest approach. P(no one receives his own hat) = (# of outcomes in which no one receives his own hat)/(TOTAL number of outcomes) ...”
November 8, 2018
Brent@GMATPrepNow posted a reply to There are 27 different three-digit integers that can be in the Problem Solving forum
“Yes, great work, Mitch! I thought I''d mention that, once we know the correct answer is a multiple of 222 (which is also a multiple of 3), then the correct answer will be a multiple of 3. Useful property: If a number is a multiple of 3, then the sum of its digits is also a multiple of 3. When we ...”
November 7, 2018
Brent@GMATPrepNow posted a new topic called Challenge: Al, Bob, Cal and Don each own 1 hat. If the 4... in the Problem Solving forum
“Al, Bob, Cal and Don each own 1 hat. If the 4 hats are randomly distributed so that each man receives exactly 1 hat, what is the probability that no one receives his own hat? A) 1/8 B) 1/4 C) 1/3 D) 3/8 E) 1/2 Answer: D Difficulty level: 650 – 700 Source: www.gmatprepnow.com”
November 7, 2018
Brent@GMATPrepNow posted a reply to If x, y and z are non-negative integers such that x < y & in the Problem Solving forum
“I created this question to show that there can be times when the best (i.e., fastest) way to solve a counting question is by listing and counting How do we know when it''s not a bad idea to use listing and counting? The answer choices will tell us (ALWAYS scan the answer choices before ...”
November 7, 2018
Brent@GMATPrepNow posted a reply to How many men are in a certain company's vanpool program? in the Data Sufficiency forum
“Target question: How many men are in a certain company''s vanpool program? Statement 1: The ratio of men to women in the program is 3 to 2. Let''s TEST some values. There are several scenarios that satisfy statement 1. Here are two: Case a: There are 3 men and 2 women in the program. In ...”
November 7, 2018
Brent@GMATPrepNow posted a reply to Speed Time Distance MGMAT in the Problem Solving forum
“GIVEN: When the men start walking, Brian has a 30-mile lead Let B = Brian''s walking speed (in miles per hour) Let A = Ashok''s walking speed (in miles per hour) Since Ashok''s speed is greater than Brian''s speed, the rate at which the gap shrinks = (A - B) miles per hour For example, if A ...”
November 6, 2018
Brent@GMATPrepNow posted a reply to 2019 GMAC Official Guide applicable for 60-Day Study Guide? in the The 60-Day GMAT Study Guide forum
“If you go here (https://www.gmatprepnow.com/content/improvement-chart) and download the Improvement Chart for the OG2016, you''ll see the question breakdown for each topic. This should help. Cheers, Brent”
November 6, 2018
Brent@GMATPrepNow posted a reply to In a certain game, a large bag is filled with blue, green, in the Problem Solving forum
“This question begs for some prime factorization. 88,000 = (2)(2)(2)(2)(2)(2)(5)(5)(5)(11) First, we can see that there must be one (11-point) red chip. Now, what role do these 2''s play? Since there are no 2''s hiding among the 5-point chips or the 11-point chips, the 2''s must be associated ...”
November 6, 2018
Brent@GMATPrepNow posted a reply to [x] is the greatest integer less than or equal x, what is th in the Problem Solving forum
“GIVEN: For example, [3.2] = 3, since 3 is the greatest integer that is less than (or equal) to 3.2 Likewise, [8.7] = 8, since 8 is the greatest integer that is less than (or equal to) 8.7 Now onto the question.... √25 = 5 √36 = 6 √49= 7 √64 = 8 Since √30 is BETWEEN √25 ...”
November 6, 2018
Brent@GMATPrepNow posted a reply to If in k+1 years from now John will be m years old, then how in the Problem Solving forum
“In k+1 years from now John will be m years old So, m - (k + 1) = John''s PRESENT age How old was John t-1 years ago? So, m - (k + 1) - (t - 1) = John''s age (t-1) YEARS AGO Simplify m - (k + 1) - (t - 1) to get: m - k - t Answer: A Cheers, Brent”
November 6, 2018
Brent@GMATPrepNow posted a reply to Pipe A runs 30 liters of water per minute into a pool that in the Problem Solving forum
“Let''s determine the COMBINED RATE of the two pipes Given: Pipe A''s RATE = 30 liters per minute This is equivalent to 1800 liters per HOUR Pipe B fills a third of the pool in 6 hours So, Pipe B fills the ENTIRE pool (3600 liters) in 18 hours Rate = Output/time = 3600/18 = 200 liters ...”
November 6, 2018
Brent@GMATPrepNow posted a new topic called If x, y and z are non-negative integers such that x < y < z, in the Problem Solving forum
“If x, y and z are non-negative integers such that x < y < z, then the equation x + y + z = 11 has how many distinct solutions? A) 5 B) 10 C) 11 D) 22 E) 78 Answer: B Difficulty level: 600-650 Source: www.gmatprepnow.com”
November 5, 2018
Brent@GMATPrepNow posted a reply to Challenge question: Is |1 - 4k| < k? in the Data Sufficiency forum
“Target question: Is |1 - 4k| < k? Statement 1: k > 4x³ This pretty much tells is that k can have ANY value. For example, notice that, if x = -100, then 4x³ = -4,000,000 So, for this value of x, k can be any number greater than -4,000,000 Let''s TEST some values. There are ...”
November 5, 2018
Brent@GMATPrepNow posted a reply to Which sport utility vehicle has a higher list price, the in the Data Sufficiency forum
“Target question: Which sport utility vehicle has a higher list price, the Touristo of the Leisure? Statement 1: The list price of the Leisure is 5/6 the list price of the Touristo. If the Leisure''s price is 5/6 of the Touristo''s price, then the answer to the target question is the Touristo ...”
November 5, 2018
Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“Here''s our video on Range and Standard Deviation https://www.youtube.com/watch?v=FbAlIjw2fwY Cheers, Brent”
November 5, 2018
Brent@GMATPrepNow posted a reply to If xy=-18, is x less than y? in the Data Sufficiency forum
“ Given: xy = -18 Target question: is x less than y? Statement 1: x < 0 In other words, x is NEGATIVE So, our given information (xy = -18) becomes: (NEGATIVE)(y) = -18 In other words: (NEGATIVE)(y) = NEGATIVE This tells us that y is POSITIVE If y is POSITIVE, and x is NEGATIVE, the ...”
November 4, 2018
Brent@GMATPrepNow posted a reply to Challenge #2: If x and y are different positive integers, wh in the Problem Solving forum
“i) When x is divided by y, the remainder is 2x The remainder cannot be greater than the dividend (the number we''re dividing) For example, it CANNOT be the case that 17 divided by 5 leaves a remainder of 34 Statement i can never be true Check the answer choices. . . . ELIMINATE A and D ii) ...”
November 3, 2018
Brent@GMATPrepNow posted a new topic called Challenge question: Is |1 - 4k| < k? in the Data Sufficiency forum
“Is |1 - 4k| < k? (1) k > 4x³ (2) k < 2x – x² - 2 Answer: B Difficulty level: 700+ Source: www.gmatprepnow.com”
November 3, 2018
Brent@GMATPrepNow posted a reply to If the average (arithmetic mean) of p, q, and r is 6, what i in the Data Sufficiency forum
“ Given: The average (arithmetic mean) of p, q, and r is 6 We can write: (p + q + r)/3 = 6 This means: p + q + r = 18 Target question: What is the value of r? Statement 1: p = -r Given: p + q + r = 18 Replace p with -r to get: -r + q + r = 18 Simplify: q = 18 What about the value of ...”
November 2, 2018
Brent@GMATPrepNow posted a reply to Cars J and K are making the trip from City A to City B. in the Problem Solving forum
“Car K travels at a constant speed that is 80% the constant speed of Car J Let''s assign some nice values to the speeds. Let''s say Car J travels 40 miles per hour So, Car K travels 32 miles per hour Car J departs from City A 15 minutes after Car K does Let''s calculate the distance that Car ...”
November 2, 2018
Brent@GMATPrepNow posted a reply to At a family summer party, each of the x members of the in the Problem Solving forum
“Let''s use the INPUT-OUTPUT approach. It might be useful to choose a number that works well with the fractions given in the question (1/3 and 1/7). So, let''s say there are 21 family members at the party. In other words, we''re saying that x = 21 1/3 chose to have a hamburger, and of ...”
November 1, 2018
Brent@GMATPrepNow posted a reply to When a positive integer n is divided by 19, what is the rema in the Data Sufficiency forum
“Target question: When n is divided by 19, what is the remainder? Statement 1: n-17 is a multiple of 19 ----ASIDE------------------------------------------- If N is a multiple of d, then we can write N = dk (for some integer k) For example, if N is a multiple of 5, then we can write N = 5k ...”
November 1, 2018
Brent@GMATPrepNow posted a reply to In the diagram above, points A, B, C, D, and E represent the in the Problem Solving forum
“points A, B, C, D, and E represent the five teams in a certain league in which each team must play each of the other teams exactly once. Let''s first determine the total number of games that will be played. There are 5 teams, so each team will play 4 games (since a team can''t play itself) So, ...”
November 1, 2018
Brent@GMATPrepNow posted a reply to In four years, Andy will be twice as old as Betsy. How old in the Data Sufficiency forum
“ Given: In four years, Andy will be twice as old as Betsy. Let A = Andy''s PRESENT age Let B = Betsy''s PRESENT age So, A+4 = Andy''s age IN 4 YEARS And so, B+4 = Betsy''s age IN 4 YEARS If Andy will be twice as old as Betsy IN 4 YEARS, we can write: A+4 = 2(B+4) Expand: A + 4 = 2B + 8 ...”
October 31, 2018
Brent@GMATPrepNow posted a reply to If m and n are integers, is m+m^2-n an even number? in the Data Sufficiency forum
“ Given: m and n are integers Target question: Is m + m² - n an even number? This is a good candidate for rephrasing the target question Aside: Here’s a video with tips on rephrasing the target question: We can take the expression, m + m² - n and rewrite it as m(1 + m) - n Now notice ...”
October 31, 2018
Brent@GMATPrepNow posted a reply to In 1995 a certain store had 1,800 tools in stock that had in the Problem Solving forum
“1,000 of these tools were sold in 1995 for $40 each So, the REVENUE = (1000)($40) = $40,000 The 1000 tools were purchased for $30 each. So, the EXPENSE = (1000)($30) = $30,000 PROFIT for 1995 = $40,000 - $30,000 = $10,000 ----------------------------------------------- The remaining 800 ...”
October 31, 2018
Brent@GMATPrepNow posted a reply to Tom, Bill, Robert, Roger, and Terry are standing in a row in the Problem Solving forum
“One approach is to ignore the rule and determine the total number of ways to arrange all 5 people, and then subtract the number of arrangements that BREAK the rule. I''m sure someone will post that kind of solution shortly. Here''s another approach: Take the task of arranging the 5 men and ...”
October 30, 2018
Brent@GMATPrepNow posted a new topic called Challenge #2: If x and y are different positive integers, wh in the Problem Solving forum
“If x and y are different positive integers, which of the following COULD be true: i) When x is divided by y, the remainder is 2x ii) When x is divided by 2y, the remainder is y iii) When (2x + y) is divided by (x + y), the remainder is y A) i only B) ii only C) iii only D) i & ii ...”
October 30, 2018
Brent@GMATPrepNow posted a reply to Challenge: If x and y are different positive integers, which in the Problem Solving forum
“i) When x is divided by y, the remainder is x This occurs any time x < y For example, if x = 5 and y = 7, then statement i becomes: When 5 is divided by 7, the remainder is 5 So true! Scan the answer choices....eliminate D ----------------------------------------------------- ii) When 2x ...”
October 30, 2018
Brent@GMATPrepNow posted a reply to Carmelo and LeBron participate in a seven-person footrace on in the Problem Solving forum
“Here are three similar questions to practice with: - http://www.beatthegmat.com/counting-six-mobsters-t47167.html - http://www.beatthegmat.com/permutation-and-combination-t273916.html - http://www.beatthegmat.com/permutations-with-waiting-line-t274020.html Cheers, Brent”
October 30, 2018
Brent@GMATPrepNow posted a reply to A certain basket contains 10 apples, 7 of which are red and in the Problem Solving forum
“Jay has demonstrated a solution that involves counting techniques. Here''s one that involves probability rules. Let''s find the probability of selecting a red apple 1st, a red apple 2nd, and a green apple 3rd (aka RRG) P(red apple 1st AND red apple 2nd AND green apple 3rd) = P(red apple 1st) x ...”
October 30, 2018
Brent@GMATPrepNow posted a reply to A salesperson for an automobile dealer earns an annual in the Problem Solving forum
“Total earnings = (base salary) + (commission) base salary = $25,000 commission = 10% of total sales OVER $100,000 = 10% of (x - $100,000) = 0.1(x - $100,000) So, total earnings = $25,000 + 0.1(x - $100,000) Answer: E Cheers, Brent”
October 30, 2018
Brent@GMATPrepNow posted a reply to There are 16 teams in a soccer league, and team plays each in the Problem Solving forum
“Another approach: The question is really asking, "In how many different ways can we create 2-team pairings from 16 teams?" Since the order of the selections does not matter (i.e., selecting teams A and B to play, is the same as selecting teams B and A to play), we can use combinations. ...”
October 30, 2018
Brent@GMATPrepNow posted a reply to There are 16 teams in a soccer league, and team plays each in the Problem Solving forum
“There are 16 teams. If we ask each team, "How many teams did you play?" we''ll find that each team played 15 teams, which gives us a total of 240 games (since 16 x 15 = 240). From here we need to recognize that each game has been COUNTED TWICE. For example, if Team A and Team B play ...”
October 30, 2018
Brent@GMATPrepNow posted a reply to For integers a, b, c, a/(b - c)=1 what is the value of (b-c) in the Data Sufficiency forum
“ Given: a/(b - c) = 1 Target question: What is the value of (b-c)/b ? This is a good candidate for rephrasing the target question. Aside: Here’s a video with tips on rephrasing the target question: If a/(b - c) = 1, then we know that a = b - c The target question asks "What is the ...”
October 29, 2018
Brent@GMATPrepNow posted a reply to If a and b are integers such that a > b > 1, which of in the Problem Solving forum
“Let''s make an important observation. Some positive multiples of 3 are: 3, 6, 9, 12, . . . . Some positive multiples of 5 are: 5, 10, 15, 20, . . . . Some positive multiples of 12 are: 12, 24, 36, 48, . . . . General observation: the positive multiples of k are all greater than or equal to k ...”
October 29, 2018
Brent@GMATPrepNow posted a new topic called Challenge: If x and y are different positive integers, which in the Problem Solving forum
“If x and y are different positive integers, which of the following COULD be true: i) When x is divided by y, the remainder is x ii) When 2x is divided by y, the remainder is x iii) When x+y is divided by x , the remainder is x-y A) i only B) i & ii only C) i & iii only D) ii & ...”
October 29, 2018
Brent@GMATPrepNow posted a reply to What is the value of x? in the Data Sufficiency forum
“Target question: What is the value of x? Statement 1: (x + 2)(x + 3) = 0 This means that EITHER x = -2 OR x = -3 Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT Statement 2: x² + 5x + 6 = 0 Factor the left side of the equation to get: (x + 2)(x ...”
October 29, 2018
Brent@GMATPrepNow posted a reply to A length of rope is cut into three different lengths. What in the Data Sufficiency forum
“Target question: What is the length of the shortest rope? Let''s assign some variables. Let x = length of shortest rope Let y = length of middle rope Let z = length of longest rope Statement 1: The combined length of the longest two pieces is 6 feet. In other words, y + z = 6 Since we ...”
October 28, 2018
Brent@GMATPrepNow posted a reply to Challenge question: At noon, Joe and a hummingbird leave in the Problem Solving forum
“The main idea here is that all 3 travelers travel for the SAME amount of time. So, let''s first determine the time it takes for Joe and Sue to meet. This is a shrinking gap question. To determine the rate at which the gap shrinks, we''ll ADD the travel speeds of Joe and Sue That is, ...”
October 28, 2018
Brent@GMATPrepNow posted a reply to If x and y are positive, what is the value of y ? in the Data Sufficiency forum
“Target question: What is the value of y? Given: x and y are positive Statement 1: xy is the square of an integer. There are several values of x and y that satisfy this condition. Here are two: Case a: x = 1 and y = 1. Here xy = (1)(1) = 1, which is the square of an integer. In this ...”
October 28, 2018
Brent@GMATPrepNow posted a new topic called Challenge question: At noon, Joe and a hummingbird leave in the Problem Solving forum
“At noon, Joe and a hummingbird leave point A and travel towards point B, which is 12 miles away. At the same time Sue leaves point B and travels toward point A. Joe, Sue and the hummingbird travel at constant speeds of 3 miles per hour, 4 miles per hour, and 84 miles per hour respectively. When the ...”
October 27, 2018
Brent@GMATPrepNow posted a reply to There are n students in a class. Of them, k boys and k girls in the Data Sufficiency forum
“Target question: What is the probability that Harvey will be paired with Jessica? Given: There are n students in a class. Of them, k boys and k girls (including Harvey and Jessica) are selected for a dance performance in which students will dance in pairs of one boy and one girl. ...”
October 27, 2018
Brent@GMATPrepNow posted a reply to When the positive integer n is divided by 25, the remainder in the Data Sufficiency forum
“Target question: What is the value of n? Given: When the positive integer n is divided by 25, the remainder is 13. -------ASIDE------------- When it comes to remainders, we have a nice rule that says: If N divided by D leaves remainder R, then the possible values of N are R, R+D, R+2D, ...”
October 27, 2018
Brent@GMATPrepNow posted a reply to A circus clown is entertaining kids by making balloon in the Problem Solving forum
“As with many probability questions, we can solve this by using counting techniques or rules of probability. Let''s use rules of probability P(balloon animal is an elephant) = 1/4 P(balloon animal is purple) = 1/5 P(clown makes a purple elephant balloon animal) = P(balloon animal is ...”
October 27, 2018
Brent@GMATPrepNow posted a reply to In a right triangle, the longer leg is two more than three in the Problem Solving forum
“In a right triangle, the longest side is called the hypotenuse, and the two sides that meet to create a 90-degree angle are called the legs. So, one leg will be the triangle''s base, and the other leg will be the triangle''s height. Let x = length of the triangle''s base (which, for this ...”
October 27, 2018
Brent@GMATPrepNow posted a reply to If a and b are two positive numbers, what is the product of in the Data Sufficiency forum
“Target question: What is the value of ab? Statement 1: The LCM of a and b is 16 Let''s TEST some values. There are several values of a and b that satisfy statement 1. Here are two: Case a: a = 1 and b = 16 (the LCM of 1 and 16 is 16). In this case, the answer to the target question is ab = ...”
October 26, 2018
Brent@GMATPrepNow posted a reply to In the mid-1960's a newly installed radar warning system in the Sentence Correction forum
“The idiom here is "Mistake x FOR y" So, we can eliminate A, C and E We''re left with B and D D conveys an ambiguous message, because it suggests that the moon was rising for an attack. ELIMINATE D Answer: B Cheers, Brent”
October 26, 2018
Brent@GMATPrepNow posted a reply to What is the largest prime factor of the expression 3^8 − 2 in the Problem Solving forum
“There''s a difference of squares "hiding" in the expression 3^8 − 2^12 That is 3^8 − 2^12 = (3^4)² − (2^6)² We know that: x² - y² = (x + y)(x - y) So, we get: (3^4)² − (2^6)² = (3^4 + 2^6)(3^4 - 2^6) = (81 + 64)(81 - 64) = (145)(17) = (5)(29)(17) The greatest ...”
October 26, 2018
Brent@GMATPrepNow posted a reply to When Q is divided by W, the quotient is R and the remainder in the Problem Solving forum
“-----ASIDE----------------------- There''s a nice rule that says, "If N divided by D equals Q with remainder R, then N = DQ + R" For example, since 17 divided by 5 equals 3 with remainder 2, then we can write 17 = (5)(3) + 2 Likewise, since 53 divided by 10 equals 5 with remainder 3, ...”
October 26, 2018
Brent@GMATPrepNow posted a reply to Tricky: If AB || DE, and AB = 10, what is the length of DE? in the Data Sufficiency forum
“Let''s first add the given information (and their implications) to the diagram If AB || DE, we know that ∠BAC = ∠CED and ∠ABC = ∠DCE Also, since vertically opposite angles are equal, we know that ∠ACB = ∠DCE https://i.imgur.com/fgDp7Yh.png Now that we''ve identified 3 pairs of ...”
October 26, 2018
Brent@GMATPrepNow posted a new topic called Tricky: If AB || DE, and AB = 10, what is the length of DE? in the Data Sufficiency forum
“https://i.imgur.com/jyTAK6n.png If AB || DE, and AB = 10, what is the length of DE? (1) BC = 6 and CE = 4 (2) DC = 3 and CB = 6 Answer: B Difficulty level: 650 – 700 Source: www.gmatprepnow.com”
October 25, 2018
Brent@GMATPrepNow posted a reply to If |x-6|=2x, then x=? in the Problem Solving forum
“There are 3 steps to solving equations involving ABSOLUTE VALUE: 1. Apply the rule that says: If |x| = k, then x = k or x = -k 2. Solve the resulting equations 3. Plug solutions into original equation to check for extraneous roots Step 1: x - 6 = 2x or x - 6 = -2x case a: x - 6 = 2x Step ...”
October 25, 2018
Brent@GMATPrepNow posted a reply to CHALLENGE: 10 teams (A, B, C, D, E, F, G, H, I and J) partic in the Problem Solving forum
“First determine the TOTAL number of games played. We can select 2 teams from 10 teams in 10C2 ways (= 45 ways) So, there will be 45 games in TOTAL IMPORTANT: Each team plays 9 games For each game, 2 points are awarded. So, the TOTAL number of POINTS awarded = (2)(45) = 90 Teams A, B, C, ...”
October 24, 2018
Brent@GMATPrepNow posted a reply to Noelle walks from point A to point B at an average speed of in the Problem Solving forum
“For these kinds of questions, I typically follow the approach that Fabio used (assign a nice value to the distance). But we can also solve the question algebraically: Let d = the distance between Points A and B. Let x = the Noelle''s speed from Point B to Point A. We want the average ...”
October 24, 2018
Brent@GMATPrepNow posted a reply to What is the median number of employees assigned per project in the Data Sufficiency forum
“Target question: What is the median number of employees assigned per project? Statement 1: 25 percent of the projects at Company Z have 4 or more employees assigned to each project. Let''s pretend that there are 4 projects altogether. There are several sets of values that meet this condition. ...”
October 24, 2018
Brent@GMATPrepNow posted a reply to In a certain company, the ratio of the number of manager to in the Problem Solving forum
“One option is to use TWO VARIABLES Let M = CURRENT # of managers Let W = CURRENT # of production-line workers The ratio of the number of managers to the number of production-line workers is 5 to 72. So, we can write: M/W = 5/72 Cross multiply to get: 5W = 72M If 8 additional ...”
October 23, 2018
Brent@GMATPrepNow posted a reply to When 100 is divided by positive integer x, the remainder is in the Problem Solving forum
“A fast approach is to find a value of x that meets the given condition: When 100 is divided by positive integer x, the remainder is 2 Well, x = 98 satisfies that condition, since 100 divided by 98 = 1 with remainder 2 What is the remainder when 198 is divided by x? Well, 198 divided by 98 ...”
October 23, 2018
Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“Range and Standard Deviation Video: https://www.youtube.com/watch?v=FbAlIjw2fwY Cheers, Brent”
October 23, 2018
Brent@GMATPrepNow posted a reply to Which of the following values, when inserted into the set of in the Problem Solving forum
“Let''s test each answer choice.... A. 2 The new set becomes {2, 5, 10, 12, 13, 17, 22, 22} Since we have an EVEN number of values in the set, the median equals the average of the two middlemost numbers. So, median = (12 + 13)/2 = 25/2 = 12.5 No good - we want the median to be 15 B. ...”
October 23, 2018
Brent@GMATPrepNow posted a reply to What are the coordinates of point B in the figure above ? in the Data Sufficiency forum
“IMPORTANT: For geometry Data Sufficiency questions, we are typically checking to see whether the statements "lock" a particular angle, length, or shape into having just one possible measurement. This concept is discussed in much greater detail in the video below. Target question: What ...”
October 23, 2018
Brent@GMATPrepNow posted a reply to The range of set A is 24 and the range of set B is 20. What in the Problem Solving forum
“If the range of set A is 24, and we add more values (from set B) to set A, then the range of the resulting set must be greater than or equal to 24 (that is, the range of a set cannot get smaller upon adding MORE numbers to that set). For this reason, we can ELIMINATE answer choice A. From ...”
October 23, 2018
Brent@GMATPrepNow posted a reply to If x and y are positive integers, what is the remainder when in the Data Sufficiency forum
“ Given: x and y are positive integers Target question: What is the remainder when x^y is divided by 10? This is a good candidate for rephrasing the target question. Notice that 43 divided by 10 leaves remainder 3, and 127 divided by 10 leaves remainder 7, and 618 divided by 10 leaves ...”
October 23, 2018
Brent@GMATPrepNow posted a new topic called CHALLENGE: 10 teams (A, B, C, D, E, F, G, H, I and J) partic in the Problem Solving forum
“10 teams (A, B, C, D, E, F, G, H, I and J) participate in a soccer tournament in which each team plays every other team once. For each game played, points are awarded to the teams as follows: 0 points for losing the game 1 point each for tying the game 2 points for winning the game After ...”
October 22, 2018
Brent@GMATPrepNow posted a reply to Clarissa will create her summer reading list by randomly in the Problem Solving forum
“Take the task of creating the reading list and break it into stages. Stage 1: Select a book to read 1st There are 10 books to choose from. So, we can complete stage 1 in 10 ways Stage 2: Select a book to read 2nd There are 9 books remaining to choose from (since we already chose a book ...”
October 22, 2018
Brent@GMATPrepNow posted a reply to A jar contains only green pencils and red pencils. If the in the Data Sufficiency forum
“Target question: What percentage of the pencils are green? Given: The jar contains only green pencils and red pencils. Statement 1: The jar contains 75 red pencils. If 75 of the 225 pencils are red, then the remaining 150 pencils are GREEN. 150/225 = 2/3 = 66 2/3%, so the answer to ...”
October 22, 2018
Brent@GMATPrepNow posted a reply to Challenge Question: In the x-y coordinate plane, does line k in the Data Sufficiency forum
“Target question: Does line k have a positive x-intercept? Statement 1: (slope of line k)(y-intercept of line k) > 0 There are two possible cases that that satisfy statement 1: - the slope and y-intercept are both positive - the slope and y-intercept are both negative Let''s examine ...”
October 21, 2018
Brent@GMATPrepNow posted a reply to What is the area of the triangle formed by the intersection in the Problem Solving forum
“Here''s a similar question to practice with: https://www.beatthegmat.com/area-of-triangle-formed-by-intersections-of-3-lines-t276079.html Cheers, Brent”
October 21, 2018
Brent@GMATPrepNow posted a new topic called Challenge Question: In the x-y coordinate plane, does line k in the Data Sufficiency forum
“In the x-y coordinate plane, does line k have a positive x-intercept? (1) (slope of line k)(y-intercept of line k) > 0 (2) (slope of line k) - (y-intercept of line k) < 0 Answer: A Difficulty level: 650 – 700 Source: www.gmatprepnow.com”
October 19, 2018
Brent@GMATPrepNow posted a reply to When positive integer N is divided by positive integer J, in the Problem Solving forum
“ASIDE: 7/2 = 3 1/2 = 3 + 0.5 = 3.5 Notice that 1 is the remainder when we divide 7 by 2. 23/5 = 4 3/5 = 4 + 0.6 = 4.6 Notice that 3 is the remainder when we divide 23 by 5. 31/4 = 7 3/4 = 7 + 0.75 = 7.75 Notice that 3 is the remainder when we divide 31 by 4. GIVEN: N/J = 134.08 This means ...”
October 19, 2018
Brent@GMATPrepNow posted a reply to If there are more than two numbers in a certain list, is in the Data Sufficiency forum
“[quote="Jay@ManhattanReview"] Hey Jay, I thought I should point out that case 2 doesn''t satisfy the statement. If we choose 1 and 2 from the set, then the product isn''t 0. That said, {0, 0, 0, 0, 1} meets the given condition, as does {0, 0, 0, 0, 0, 0, 0, 3} etc Cheers, ...”
October 19, 2018
Brent@GMATPrepNow posted a reply to If -1<x<0, Which of the following is listed in ascendi in the Problem Solving forum
“Let''s test a value of x. If -1 < x < 0, then x COULD equal -1/2 So, x^(-1) = (-1/2)^(-1) = 1/(-1/2) = -2 And, x^(-2) = (-1/2)^(-2) = 1/(-1/2)^2 = 1/(1/4) = 4 And, x^2 = (-1/2)^2 = 1/4 Listed in ascending order, we get: -2, 1/4, 4 In other words, x^(-1), x^2, x^(-2) Answer: A ...”
October 19, 2018
Brent@GMATPrepNow posted a reply to The latest model of space shuttle can achieve a maximum in the Problem Solving forum
“GIVEN: The shuttle can travel 25 miles in 1 second So, the shuttle can travel 1500 miles in 60 seconds In other words, the shuttle can travel 1500 miles in 1 MINUTE So, the shuttle can travel 90,000 miles in 60 MINUTES In other words, the shuttle can travel 90,000 miles in 1 HOUR In other ...”
October 18, 2018
Brent@GMATPrepNow posted a reply to A jar contains 6 red marbles and 9 blue marbles. If Evelyn in the Problem Solving forum
“P(both are same color) = P(1st marble is red AND 2nd marble is red OR 1st marble is blue AND 2nd marble is blue) = x P(2nd marble is red)] + x P(2nd marble is blue)] = x 5/14] + x 8/14] = x 5/14] + x 8/14] = 10/70 + 24/70 = 34/70 = 17/35 Answer: D Cheers, Brent”
October 18, 2018
Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“Time management strategy for test day Video: https://www.youtube.com/watch?v=bWrUiBT83PQ Cheers, Brent”
October 18, 2018
Brent@GMATPrepNow posted a reply to In the x-y coordinate plane, line k passes through in the Problem Solving forum
“Notice that, if the line passes through the origin, then the line has slope -4/5 (aka a slope of -0.8), but the line will not have a negative x-intercept Notice that, if the line passes through the (0,4), then the line will have slope 0, BUT the line will not have a negative x-intercept. See ...”
October 18, 2018
Brent@GMATPrepNow posted a reply to f[f{f(x)}]=??? in the GMAT Math forum
“Useful property: 1/(a/b) = b/a We want: ff(5)}] = f1/6}] f{1/6} = 1/(1 + 1/6) = 1/(7/6) = 6/7 So, ff{1/6}] = f6/7] Finally, f[6/7] = 1/(1 + 6/7) = 1/(13/7) = 7/13 Answer: B (since 21/39 reduces to the equivalent fraction 7/13) Cheers, Brent”
October 18, 2018
Brent@GMATPrepNow posted a reply to In the month of August, Pentheus Corporation made $200,000 in the Problem Solving forum
“In the month of August, Pentheus Corporation made $200,000 in profit. Pentheus made 6% of that profit on the second Wednesday of August. 1% of $200,000 = $2,000, so 6% of $200,000 = (6)($2,000) = $12,000 So, the profit on that day = $12,000 If the profits that day were approximately 14.5% of ...”
October 18, 2018
Brent@GMATPrepNow posted a reply to Brian purchased a bouquet of 40 flowers for his mother for in the Problem Solving forum
“We can solve this question using either 1 variable or 2 variables. Here''s an approach that involves 1 variable: Let t = # of tulips in bouquet So. 40 - t = # of roses in bouquet So, ($1.00)(t) = the total COST of all t tulips And ($1.50)(40 - t) = the total COST of all 40-t roses ...”
October 18, 2018
Brent@GMATPrepNow posted a reply to In a town of 8,000 residents, 65 percent of all residents in the Problem Solving forum
“Another approach is to use the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it (aka overlapping sets questions). Here, we have a population of residents, and the two characteristics are: ...”
October 17, 2018
Brent@GMATPrepNow posted a reply to What is the remainder if 7^10 is divided by 100? in the Problem Solving forum
“Sweeeeeeeeeeeeet solution, Scott!! Cheers, Brent”
October 17, 2018
Brent@GMATPrepNow posted a reply to If x, y, and z are all nonzero numbers, and x = y + z, which in the Problem Solving forum
“NOTE: this is one of those questions that require us to check/test each answer choice. In these situations, always check the answer choices from E to A, because the correct answer is typically closer to the bottom than to the top. For more on this strategy, see my article: ...”
October 16, 2018
Brent@GMATPrepNow posted a reply to Set X consists of different positive numbers arranged in in the Data Sufficiency forum
“Target question: What is the arithmetic mean of set X? Given: Set X consists of different positive numbers arranged in ascending order: K, L, M, 5, 7. K, L and M are consecutive integers This means that EITHER K, L, M = 1, 2, 3 respectively, OR K, L, M = 2, 3, 4 respectively Head straight ...”
October 16, 2018
Brent@GMATPrepNow posted a reply to A Martian bat flies at 60 yards per second from its nest to in the Problem Solving forum
“Rich''s approach is definitely the best (i.e., fastest) way to solve this question. However, if the answer choices weren''t so sweet, here''s an algebraic solution Average speed = (total distance traveled)/(total travel time) Let''s assign nice values to the distances. These values should ...”
October 16, 2018
Brent@GMATPrepNow posted a reply to Charlie takes 2.5 hours to fly from Los Angeles to Mexico in the Problem Solving forum
“Average speed = (total distance traveled)/(total travel time) So, Average speed = 1200/2.5 = 2400/5 = 4800/10 = 480 mph Answer: D Cheers, Brent”
October 16, 2018
Brent@GMATPrepNow posted a reply to A certain NYC taxi driver has decided to start charging a in the Problem Solving forum
“Here''s an algebraic approach: A certain taxi driver charges a rate of r CENTS per person per mile r CENTS = r/100 DOLLARS Since there are 3 people, the rate is (3)(r/100) DOLLARS per mile In other words, the rate is 3r/100 dollars per mile. With a 50% discount, the new rate = ...”
October 16, 2018
Brent@GMATPrepNow posted a new topic called In the x-y coordinate plane, line k passes through in the Problem Solving forum
“In the x-y coordinate plane, line k passes through the point (5, -4) and has a negative x-intercept. Which of the following COULD be the equation of line k? i) y = -0.4x - 2 ii) y = 2 - 1.2x iii) y = -0.7x - 1.5 A) i only B) ii only C) iii only D) i & ii only E) i & iii only ...”
October 16, 2018
Brent@GMATPrepNow posted a reply to Lindsay can paint 1/x of a certain room in one hour. If in the Problem Solving forum
“This appears to be a slightly different version of this official question: https://www.beatthegmat.com/work-rate-problem-5-t292679.html HOWEVER, unless I''m missing something, the correct answer is missing. Cheers, Brent”
October 15, 2018
Brent@GMATPrepNow posted a reply to How many factors does the number X have? in the Data Sufficiency forum
“Target question: How many factors does the number X have? Statement 1: X is divisible by 47 Let''s TEST some values. There are several values of X that satisfy statement 1. Here are two: Case a: X = 47. The factors of 47 are {1, 47}. So, the answer to the target question is X has 2 ...”
October 15, 2018
Brent@GMATPrepNow posted a reply to A rectangular solid S, has dimensions 4 by 9 by k. What is in the Data Sufficiency forum
“Target question: What is the value of k? Given: A rectangular solid S, has dimensions 4 by 9 by k Statement 1: 4 < k < 9 Since k can have ANY value between 4 and 9, statement 1 is NOT SUFFICIENT Statement 2: A cube of side 6 has the same volume as rectangular solid S. So ...”
October 15, 2018
Brent@GMATPrepNow posted a reply to In the rectangular coordinate system above, if the in the Data Sufficiency forum
“I think that, if this were an official GMAT question, the correct answer would be E (not B), because we aren''t specifically told that the dotted lines are parallel to the x-axis and the y-axis. If those dotted lines aren''t parallel to those axes, the we can''t determine the value of y. ...”
October 15, 2018
Brent@GMATPrepNow posted a reply to In the figure above, triangle ABC is equilateral, and point in the Problem Solving forum
“It may help to add some lines to the diagram. First add lines from the center to the 3 vertices. https://s8.postimg.cc/e412m8uq9/clk1.jpg Aside, we know that each angle is 120º since all three (equivalent) angles must add to 360.º Then draw a circle so that the triangles vertices are on ...”
October 15, 2018
Brent@GMATPrepNow posted a reply to The mass of 1 cubic meter of a substance is 800 kg under in the Problem Solving forum
“GIVEN: 1 cubic METER of the substance weighs 800 KILOGRAMS 1 kg =1,000 grams, so we can write: 1 cubic METER of the substance weighs 800,000 GRAMS 1 cubic meter = 1,000,000, so we can write: 1,000,000 cubic CENTIMETERS of the substance weighs 800,000 GRAMS What is the volume in cubic ...”
October 14, 2018
Brent@GMATPrepNow posted a reply to At a family summer party, each of the x members of the in the Problem Solving forum
“These kinds of questions (Variables in the Answer Choices - VIACs) can be answered algebraically or using the INPUT-OUTPUT approach. The Ash Mo solved the question algebraically, so let''s use the INPUT-OUTPUT approach. It might be useful to choose a number that works well with the fractions ...”
October 13, 2018
Brent@GMATPrepNow posted a reply to When A and B are positive integers, is AB a multiple of 4? in the Data Sufficiency forum
“Target question: Is AB a multiple of 4? Useful property: If N is divisible by d, we can say that N = dk for some integer k For example, if N is divisible by 5, we can say that N = 5k for some integer k Statement 1: The greatest common divisor of A and B is 6 This means that A is divisible ...”
October 13, 2018
Brent@GMATPrepNow posted a reply to How much time did it take a certain car to travel 400 in the Data Sufficiency forum
“Target question: How long did it take to travel 400km To find the travel time, we need to know the average speed traveled. Let x = the average speed traveled. REPHRASED target question: What is the value of x? Statement 1: The car traveled the first 200 km in 2.5 hrs No info about the ...”
October 13, 2018
Brent@GMATPrepNow posted a reply to Challenge question: What is the sum of all in the Problem Solving forum
“Approach #1 If we recognize that x^(2/3) = u-substitution. Let u = x^(1/3) Now take original equation and replace x^(1/3) with u to get: u² - u - 2 = 4 Subtract 4 from both sides to get: to get: u² - u - 6 = 0 Factor: (u - 3)(u + 2) = 0 So, the two solutions here are u = 3 and u = -2 ...”
October 13, 2018
Brent@GMATPrepNow posted a reply to A certain club has 10 members, including Harry. One of the 1 in the Problem Solving forum
“As with many probability questions, we can solve this using counting techniques or probability rules. So, before you embark on one approach, try to determine which one is faster. Here''s the probability approach: P(Harry selected Secretary or Treasurer) = 1 - P(Harry selected president OR ...”
October 13, 2018
Brent@GMATPrepNow posted a reply to The average age of a group of n people is 15 yrs. One more in the Problem Solving forum
“The average age of a group of n people is 15 yrs. So, (sum of all n ages)/n = 15 Multiply both sides by n to get: (sum of all n ages) = 15n One more person aged 39 joins the group and the new average is 17 yrs. IMPORTANT: Once this 39-year-old is added to the group, the (NEW sum of ages) = ...”
October 12, 2018
Brent@GMATPrepNow posted a new topic called Challenge question: What is the sum of all in the Problem Solving forum
“What is the sum of all solutions to the equation x^(2/3) - x^(1/3) - 2 = 4? A) -35 B) -19 C) 7 D) 19 E) 35 Answer: D Source: www.gmatprepnow.com Difficulty level: 600 - 650”
October 12, 2018
Brent@GMATPrepNow posted a reply to Challenge question: j and k are positive integers in the Data Sufficiency forum
“ Given: n = 10^j + k Target question: Is n divisible by 15? Key concepts: - If n is divisible by 15, then n must be divisible by 3 AND by 5 - If n is divisible by 3, then the sum of n''s digits must be divisible by 3 (for example, we know that 747 is divisible by 3, because 7+4+7 = 18, ...”
October 12, 2018
Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“Here''s our video on "if" versus "whether" https://www.youtube.com/watch?v=F2ZHtB088us Cheers, Brent”
October 11, 2018
Brent@GMATPrepNow posted a new topic called Challenge question: j and k are positive integers in the Data Sufficiency forum
“j and k are positive integers, and n = 10^j + k. Is n divisible by 15? (1) j and k are each divisible by 3 (2) j and k are each divisible by 5 Answer: A Difficulty level: 700+ Source: www.gmatprepnow.com”
October 11, 2018
Brent@GMATPrepNow posted a reply to Julie opened a lemonade stand and sold lemonade in two in the Data Sufficiency forum
“This question illustrates a common trap on the GMAT. For statement 2, we''re able to write the equation 52x + 58y = 492 , and in high school we learned that, if we''re given 1 equation with 2 variables, we cannot find the value of either variable. However, if we restrict the variables to ...”
October 11, 2018
Brent@GMATPrepNow posted a reply to There are 5 cars to be displayed in 5 parking spaces with in the Problem Solving forum
“Let R, R, R, B, Y represent the cars (by their colors) Notice that the three R''s are identical. So, the question becomes In how many different ways can we arrange the letters R, R, R, B and Y? ----------------ASIDE------------------------------ When we want to arrange a group of items in ...”
October 10, 2018
Brent@GMATPrepNow posted a reply to Is x/11 an integer? in the Data Sufficiency forum
“Target question: Is x/11 an integer? Statement 1: 5x/11 is an integer Let''s TEST some values There are several values of x that satisfy statement 1. Here are two: Case a: x = 11. Notice that 5x/11 = 5(11)/11 = 5, which is an integer. In this case, x/11 = 11/11 = 1. So, the answer to the ...”
October 10, 2018
Brent@GMATPrepNow posted a reply to Dick and Jane each saved $3000 in 1989. In 1990 Dick save 8 in the Problem Solving forum
“Here''s the original wording: In 1990, Dick saved 8 percent more than in 1989 So, Dick''s savings in 1990 = 1.08($3000) = $3240 In 1990, Dick and Jane saved a total of $5,000. So, Jane''s savings = $5,000 - $3240 = $1760 Approximately what percent less did Jane save in 1990 than in ...”
October 10, 2018
Brent@GMATPrepNow posted a reply to Pam and Sue drove in the same car to a business meeting that in the Problem Solving forum
“Travel time = distance/speed Pam''s travel time = 120 miles/60 mph =2 hours Sue''s travel time = 120 miles/50 mph =2.4 hours Time difference = 2.4 hours - 2 hours = 0.4 hours To convert 0.4 hours to minutes, recognize that 1 hour = 60 minutes So, 0.4 hours = (0.4)(60) minutes = 24 minutes ...”
October 10, 2018
Brent@GMATPrepNow posted a reply to A group of medical interns at Bohemus Medical School want to in the Problem Solving forum
“Take the task of arranging dates and break it into stages. Let A, B, C, D and E represent the 5 girls Stage 1: Select a boy to date girl A We can choose any of the 5 boys, so we can complete stage 1 in 5 ways Stage 2: Select a boy to date girl B Since we already selected a boy in ...”
October 9, 2018
Brent@GMATPrepNow posted a reply to A school library contains 200 hardcover and 300 paperback in the Problem Solving forum
“Another approach is to use the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it (aka overlapping sets questions). Here, we have a population of books, and the two characteristics are: - ...”
October 9, 2018
Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“Here''s our video on the Double Matrix Method for overlapping sets: https://www.youtube.com/watch?v=jK-tiBrrf04 Cheers, Brent”
October 9, 2018
Brent@GMATPrepNow posted a reply to If x, y, and z are positive numbers, Is z between x and y? in the Data Sufficiency forum
“Target question: Is z between x and y? Statement 1: x < 2z < y There are several sets of values of x, y and z that satisfy this condition. Here are two: Case a: x = 3, y = 10, and z = 2, in which case z is NOT between x and y Case b: x = 1, y = 10, and z = 3, in which case z IS ...”
October 9, 2018
Brent@GMATPrepNow posted a reply to If the product of X and Y is a positive number, is the sum in the Data Sufficiency forum
“IMPORTANT CONCEPTS: An ODD power preserves the sign of the base. For example, (-5)^3 = -125 and 2^5 = 32 An EVEN power always yields a positive number (as long as the base ≠ 0 For example, (-5)^4 = 625 and 2^6 = 64 Target question: Is the sum of x and y negative? Given: the ...”
October 9, 2018
Brent@GMATPrepNow posted a reply to DS: Difficulty level: 700, Source: Economist in the GMAT Math forum
“The key word here is must So, if we can find a case in which an answer choice is NOT true, then we can eliminate that answer choice. A. x is odd and y is even. x = 3 and y = 11 satisfies the condition that x/y is not an integer Since y is NOT even, we can ELIMINATE A B. x is odd and y is ...”
October 9, 2018
Brent@GMATPrepNow posted a reply to James invested $5000 in scheme A for 1 year at a simple in the Problem Solving forum
“Scheme A Interest = 5% of $5,000 = $250 Scheme B 10% interest compounded semi-annually means that the interest is compounded 2 times (in 1 year) at a rate of 5% each time One option is to apply the compound interest formula, but since we''re only compounding the interest twice, it may be ...”
October 9, 2018
Brent@GMATPrepNow posted a reply to A retailer buys cases of 24 shirts for $30/case and then in the Problem Solving forum
“The key information here is that the retailer sold all the shirts it purchased This is a huge hint! For example, we know that the retailer did NOT buy only 1 case of 24 shirts, because 24 shirts will not divide into packs of 5 shirts. Likewise, we know that the retailer did NOT buy 2 cases of ...”
October 8, 2018
Brent@GMATPrepNow posted a reply to If x^2-3x=10, what is the value of x? in the Data Sufficiency forum
“ Given: x² - 3x = 10 Subtract 10 from both sides to get: x² - 3x - 10 = 0 Factor: (x - 5)(x + 2) = 0 So, EITHER x = 5 OR x = -2 Target question: What is the value of x? Statement 1: x² - 4 = 0 Factor: (x + 2)(x - 2) = 0 So, EITHER x = -2 OR x = 2 When we combine this with the fact ...”
October 8, 2018
Brent@GMATPrepNow posted a reply to What is the greatest prime factor of 1+2+3+….+36? in the Problem Solving forum
“Useful formula: 1 + 2 + 3 + 4 + . . . . + n = (n)(n + 1)/2 So, 1 + 2 + 3 + …. + 36 = (36)(36 + 1)/2 = (36)(37)/2 = (18)(37) = (2)(3)(3)(17) So, the greatest prime factor is 37 Answer: E Cheers, Brent”
October 8, 2018
Brent@GMATPrepNow posted a reply to Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“In this short (3:25) video, we''ll examine the age-old question When do I use IF and when do we use WHETHER? Video link: https://www.youtube.com/watch?v=F2ZHtB088us Cheers, Brent”
October 7, 2018
Brent@GMATPrepNow posted a reply to All assets in Karina's investment portfolio are divided in the Problem Solving forum
“Let''s say Karina''s entire portfolio is worth $100 altogether. So, we want to divide this $100 into four integer amounts: w, x, y, z, where w < x < y < z, and we want to minimize the value of z In order to MINIMIZE the value of the z, we must MAXIMIZE the values of w, x, and y. Now ...”
October 7, 2018
Brent@GMATPrepNow posted a reply to Beth and Jim each received a salary increase. If Jim's in the Data Sufficiency forum
“Target question: Did Beth receive a greater dollar increase in salary than Jim? Given: Jim''s salary was increased by the same percent as Beth''s salary Statement 1: Before the increases, Jim''s salary was greater than $25,000. Since we have no information about Beth, there''s no way to ...”
October 7, 2018
Brent@GMATPrepNow posted a reply to Problem solving: Difficulty level: 700, Source: Jamboree in the Problem Solving forum
“Take: x² + 5|x| + 6 = 0 Subtract 6 from both sides to get: x² + 5|x| = -6 KEY CONCEPT: x² ≥ 0 and |x| ≥ 0 for all values of x In other words, x² will always be greater than or equal to 0 And |x| will always be greater than or equal to 0, which means 5|x| will always be greater than or ...”
October 7, 2018
Brent@GMATPrepNow posted a reply to TRICKY! There are n teams playing in a basketball tournam in the Problem Solving forum
“Good catch regor60! A few people alerted me to this error earlier in the day, but I was on the road and couldn''t respond. Man, I must have solved the question 3 or 4 times to make sure the numbers added up, BUT I never considered the impossibility of more than one team winning every game. ...”
October 7, 2018
Brent@GMATPrepNow posted a reply to Is -3*x^3 <= -3? in the Data Sufficiency forum
“Target question: Is (-3)(x³) ≤ -3? This is a good candidate for rephrasing the target question. Take: (-3)(x³) ≤ -3? Divide both sides by -3 to get: x³ ≥ 1 Under what circumstance will x³ be greater than or equal to 1? Well, x³ EQUALS 1 when x = 1 So, x³ will be greater than ...”
October 6, 2018
Brent@GMATPrepNow posted a reply to If x + 5 > 2 and x - 3 < 7, the value of x must be bet in the Problem Solving forum
“GIVEN: x + 5 > 2 Subtract 5 from both sides of the inequality to get: x > -3 Or we can write this as -3 < x GIVEN: x - 3 < 7 Add 3 to both sides of the inequality to get: x < 10 COMBINE the inequalities to get: -3 < x < 10 Answer: A Cheers, Brent”
October 6, 2018
Brent@GMATPrepNow posted a reply to Each year for 4 years, a farmer increased the number of in the Problem Solving forum
“Here''s another approach: First notice that, if the number of trees increases by 1/4, then the new number is 5/4 times the original number. Let x = the # of trees in the orchard at the beginning of the 4 year period. (5/4)x = # of trees after 1 year (5/4)(5/4)x = # of trees after 2 years ...”
October 5, 2018
Brent@GMATPrepNow posted a reply to Health insurance Plan A requires the insured to pay $1000 or in the Problem Solving forum
“Here''s an algebraic approach: Let T = TOTAL COST Plan A: Person pays EITHER $1000 OR 0.5T, whichever is LESS Plan B: Person pays $300 plus 20% of anything over $300. In other words, the person pays $300 + 0.2(T - 300) Since Plan A has two different scenarios, we need to test both. That ...”
October 5, 2018
Brent@GMATPrepNow posted a new topic called Bite-sized video lessons from GMAT Prep Now in the GMAT Math forum
“I thought I''d start a thread featuring some of the videos from our course. This first video is one of my favorites. It covers a useful mental-math technique called Multiplying by Doubling and Halving (length 3:25) Video link: https://www.youtube.com/watch?v=D__dWwmgq2w All the best on ...”
October 5, 2018
Brent@GMATPrepNow posted a new topic called TRICKY! There are n teams playing in a basketball tournam in the Problem Solving forum
“Several teams are competing in a basketball tournament, and each team plays every other team once. Each game has exactly 1 winner and 1 loser (no ties). If 4 teams lost exactly 5 games, 5 teams won exactly 3 games, and each of the remaining teams won all of its games, what is the total number of ...”
October 5, 2018
Brent@GMATPrepNow posted a reply to Andrew bought pizzas for his swim team. Pepperoni pizzas in the Problem Solving forum
“This question illustrates the difference between the abstract math and real world math. From the given information, we''re able to create ONE equation: 13p + 17c = 184 In high school, we learned that, if we''re given 1 equation with 2 variables, we cannot find the value of either variable, so ...”
October 5, 2018
Brent@GMATPrepNow posted a reply to ||2-3|-|2-5||=? in the Problem Solving forum
“||2-3|-|2-5|| = ||-1|-|-3|| = |1-3|| = |-2| = 2 Answer: B Cheers, Brent”
October 5, 2018
Brent@GMATPrepNow posted a reply to What is the perimeter of quadrilateral Q? in the Data Sufficiency forum
“Target question: What is the perimeter of quadrilateral Q? If we recognize that each statement alone is not sufficient, we can jump straight to...... Statements 1 and 2 combined There are several quadrilaterals that satisfy BOTH statements. Here are two: Case a: rectangle Q has ...”
October 5, 2018
Brent@GMATPrepNow posted a reply to A car salesman earns a base salary of $1,000 per month plus in the Problem Solving forum
“Let x = number of cars sold in 1 month So, his pay = $1000 + ($200)(n) If he earned $2,200 in February, how many cars does he have to sell in March in order to double his February earnings? If we double $2,200, we get $4,400 We need: $1,000 + ($200)(n) = $4400 Subtract $1,000 from both sides ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to If p and q are prime numbers, is pq+1 an odd number? in the Data Sufficiency forum
“Be careful, deloitte247 You haven''t used the information about p and q being prime numbers. Cheers, Brent”
October 4, 2018
Brent@GMATPrepNow posted a reply to In the figure above, A is the center of the circle, DF is 5, in the Problem Solving forum
“As you can see from my solution above, this question is a time-killer (even if you answer it correctly!!) So, if you''re running short on time, you can reduce the correct answers to two options, and make your best guess How so? IMPORTANT: the diagrams in GMAT problem solving questions are DRAWN ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to In the figure above, A is the center of the circle, DF is 5, in the Problem Solving forum
“As you can see from my solution above, this question is a time-killer (even if you answer it correctly) So, if you''re running short on time, you can reduce the correct answers to two options, and make your best guess How so? IMPORTANT: the diagrams in GMAT problem solving questions are DRAWN TO ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to In the figure above, A is the center of the circle, DF is 5, in the Problem Solving forum
“Let x = the length of AF https://i.imgur.com/pT36mTR.png This means AD = x + 5 = radius of the circle. This is convenient, because AE is also a radius of the circle. So, AE must have length x + 5 https://i.imgur.com/aLGqKow.png At this point, we can focus on the RIGHT TRIANGLE below: ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to If p and q are prime numbers, is pq+1 an odd number? in the Data Sufficiency forum
“ Given: p and q are prime numbers Target question: Is pq + 1 an odd number? This is a good candidate for rephrasing the target question. In order for pq + 1 to be odd, we need pq to be EVEN So, we COULD rephrase our target question as Is pq an even number?, but we can do even better than ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to A political candidate collected $1,749 from a fund raising in the Problem Solving forum
“In order to MAXIMIZE the number of contributors, we must MINIMIZE the amount that each supporter contributes. So, let''s say that each supporter contributes exactly $50 (which is the minimum about that each supporter contributes) $50 divides into $1,749 a total of 34 times (with $49 left over). ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to If x^2 + 3x + 3 = 5x + 6 then x equals in the Problem Solving forum
“nonplus2''s approach is the as mine, but a reasonably fast alternative approach is to test the answer choices . Answer choice A suggests that one possible solution is x = -1 So, plug x = -1 into the equation to get: (-1)² + 3(-1) + 3 = 5(-1) + 6 Simplify to get: 1 = 1. Perfect!!! So, x = -1 ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to A thin piece of wire 40 meters long is cut into two pieces. in the Problem Solving forum
“One approach is to plug in a value for r and see what the output should be. Let''s say r = 0. That is, the radius of the circle = 0 This means, we use the entire 40-meter length of wire to create the square. So, the 4 sides of this square will have length 10, which means the area = 100 So, ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to The price of a phone call consists of a standard connection in the Problem Solving forum
“A 10-minute call costs $2.90 and a 16-minute call costs $4.40 $4.40 - $2.90 = $1.50, and 16 minutes - 10 minutes = 6 minutes So, the extra $1.50 paid for extra 6 minutes of calling So, $0.75 would pay for 3 minutes of calling How much does a 13-minute call cost? A 10-minute call costs ...”
October 4, 2018
Brent@GMATPrepNow posted a reply to How many ounces of water must be added to 10 ounces of 3 % in the Problem Solving forum
“The original solution contains 10 ounces 3% of that is alcohol 3% of 10 = 0.3 So, the original solution contains 0.3 ounces of alcohol Let x = the amount of water (in ounces) that must be added So, the volume of the RESULTING solution = 10 + x ounces IMPORTANT: Since we''re adding water ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to Ken has a group of coins worth $6.70. He has four times as m in the Problem Solving forum
“Let x = the NUMBER of dimes So, 4x = the NUMBER of nickels And 4x - 20 = the NUMBER of quarters One dime is worth $0.1, so 0.10x = the total VALUE of the dimes (in dollars) Likewise, (0.05)(4x) = the total VALUE of the nickels (in dollars) And (0.25)(4x - 20) = the total VALUE of the ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to Goku and Vegeta are waiting in a line, are there more than 1 in the Data Sufficiency forum
“Target question: Are there more than 10 people waiting in the line? Head straight to... Statements 1 and 2 combined There are several scenarios that satisfy BOTH statements. Here are two: Case a: BACK A, B, C, D, Vegeta, Picollo, Goku, E, F, G, H FRONT. In this case, the answer to the ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to Vivian drives to her sister's house and back. She takes the in the Problem Solving forum
“One approach is to assign a "nice" value (one that works well with 50 mph and 70 mph) to the distance her sister''s house. So, let''s say the distance is 350 miles Average speed = (total distance traveled)/(total travel time) TOTAL distance = 350 miles + 350 miles = 700 miles ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to Tom’s Mom is five times as old as him. In 6 years, Tom’ in the Problem Solving forum
“Tom’s Mom is five times as old as him. Let T = Tom''s PRESENT age So, 5T = Mom''s PRESENT age This also means: Let T + 6= Tom''s age IN 6 YEARS and 5T + 6 = Mom''s age IN 6 YEARS In 6 years, Tom’s Mom will be three times as old as Tom. In other words: (Mom''s age IN 6 YEARS) = ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to A “descending number” is a three-digit number, such that in the Problem Solving forum
“Let''s use some counting methods to solve this. P(selected number is "descending") = total # of descending numbers/total # of 3-digit numbers total # of 3-digit numbers 3-digit numbers go from 100 to 999 inclusive A nice rule says: the number of integers from x to y inclusive ...”
October 3, 2018
Brent@GMATPrepNow posted a reply to Challenge question: If y < 0 < x, is x/y > -1? in the Data Sufficiency forum
“I checked the link you provided, Fabio. For me, the response from the test-makers that sticks out the most is this: "it is highly unlikely that you would come across a question with independently sufficient statements that contradict each other" I think the person answering the ...”
October 2, 2018
Brent@GMATPrepNow posted a reply to Challenge question: If y < 0 < x, is x/y > -1? in the Data Sufficiency forum
“My apologies. I posted my question without noticing its FATAL FLAW. KEY CONCEPT: On the GMAT, the two statements in a Data Sufficiency question will never contradict each other (for more on this, see the video below) Let''s examine the main issue. Statement 1: x + y > 0 Okay, so x + ...”
October 2, 2018
Brent@GMATPrepNow posted a reply to During a two-week period, the price of an ounce of silver in the Problem Solving forum
“Another approach is to test a "nice" value x A great value would be $80 (since we get $100 after we increase $80 by 25%) So, x = $80 In other words, the price of silver was $80 per ounce at the beginning of the two-week period. During a two-week period, the price of an ounce of ...”
October 2, 2018
Brent@GMATPrepNow posted a new topic called Challenge question: If y < 0 < x, is x/y > -1? in the Data Sufficiency forum
“If y < 0 < x, is x/y > -1? (1) x + y > 0 (2) 3x < -2y Answer: D Difficulty level: 600 - 650 Source: www.gmatprepnow.com”
October 2, 2018
Brent@GMATPrepNow posted a reply to For all values of x and y , let x&y be defined by x& in the Problem Solving forum
“Nice question! GIVEN: x&y = xy − x + 1 So, take the equation: (a − 2)&a = a&(a + 1) Apply rules to get the equation: (a - 2)(a) - (a - 2) + 1 = (a)(a + 1) - a + 1 Expand: a² - 2a - a + 2 + 1 = a² + a - a + 1 Simplify: a² - 3a + 3 = a² + 1 Subtract a² from both sides ...”
October 2, 2018
Brent@GMATPrepNow posted a reply to If 3 different numbers are selected from the first 8 prime n in the Problem Solving forum
“The first 8 prime numbers are: {2, 3, 5, 7, 11, 13, 17, 19} Notice that only one prime number is EVEN, and the remaining seven numbers are ODD. Also notice that the sum of 3 numbers will be EVEN only if one of the three selected numbers is 2 So, the question is really asking "What is the ...”
October 2, 2018
Brent@GMATPrepNow posted a reply to The symbol Ω represents one of the following operations: ad in the Data Sufficiency forum
“Target question: What is the value of 1 Ω 1? Given: Ω represents one of the following operations: addition, subtraction, multiplication or division. Statement 1: 2 Ω 2 = 4 2 - 2 = 0, so Ω CANNOT represent subtraction. 2 ÷ 2 = 1, so Ω CANNOT represent division. 2 + 2 = 4, so ...”
October 2, 2018
Brent@GMATPrepNow posted a reply to On a 20 mile course, Pat bicycled at an average rate of 30 in the Problem Solving forum
“Let''s start with a WORD EQUATION (Distance traveled at 30 mph) + (Distance traveled at 8 mph) = 20 miles Distance = (rate)(time) Let t = the time (in hours) Pat spent running at 8 mph Aside: 12 minutes = 1/5 hours So, we get: (30 miles per hour)(1/5 hours) + (8 miles per hour)(t ...”
October 2, 2018
Brent@GMATPrepNow posted a reply to The greatest common factor of 16 and the positive integer n in the Problem Solving forum
“Now, we can use ELIMINATION to find the correct answer. Goal: Find GCF of 210 and n. 210 = (2)(3)(5)(7) The greatest common factor of 16 and the positive integer n is 4 16 = (2)(2)(2)(2) 4 = (2)(2) So, we know for certain that the PRIME FACTORIZATION of n has TWO 2''s (and no more than ...”
October 2, 2018
Brent@GMATPrepNow posted a reply to Jan lives x floors above the ground floor of a highrise in the Problem Solving forum
“Let''s first convert 7 minutes to SECONDS in order to have uniform units of measurement. 7 minutes = 420 seconds Let''s start with a word equation Jan''s travel time (in seconds) WALKING down = Jan''s travel time (in seconds) via ELEVATOR + 420 seconds It takes her 30 seconds per floor to ...”
October 1, 2018
Brent@GMATPrepNow posted a reply to Five letters A, P, P, L and E are listed in a row. How many in the Problem Solving forum
“Here''s an approach that doesn''t require us to subtract the bad arrangements. Take the task of arranging the 5 letters and break it into stages. Stage 1: Arrange the letters A, L, E in a row We can arrange n unique objects in n! ways. So, we can arrange the 3 letters in 3! ways (= 6 ...”
October 1, 2018
Brent@GMATPrepNow posted a reply to Jevan must paint 3 rooms in a house. Room A can be painted in the Problem Solving forum
“Take the task of painting the 3 rooms and break it into stages. Stage 1: Select a color for Room A Room A can be painted orange, red or green So, we can complete stage 1 in 3 ways Stage 2: Select a color for Room B Room B can be painted orange, white or red. So we can complete this ...”
October 1, 2018
Brent@GMATPrepNow posted a reply to Improve My Overall Score in the Last Leg of Preparation? in the GMAT Strategy forum
“The resource labeled "OG2018" has questions from the 2018 OG See: https://www.beatthegmat.com/mba/official-guide-2018-library Cheers, Brent”
October 1, 2018
Brent@GMATPrepNow posted a reply to Improve My Overall Score in the Last Leg of Preparation? in the GMAT Strategy forum
“Look no further<i class="em em-grinning"></i> : https://www.beatthegmat.com/official-guide-question-library-t296755.html Cheers, Brent”
October 1, 2018
Brent@GMATPrepNow posted a reply to If m and n are integers, is mn an odd integer? in the Data Sufficiency forum
“Some important rules: #1. ODD +/- ODD = EVEN #2. ODD +/- EVEN = ODD #3. EVEN +/- EVEN = EVEN #4. (ODD)(ODD) = ODD #5. (ODD)(EVEN) = EVEN #6. (EVEN)(EVEN) = EVEN Target question: Is mn an odd integer? Given: m and n are integers Statement 1: m(n+1) is even Let''s test some ...”
October 1, 2018
Brent@GMATPrepNow posted a reply to If n is an integer, is n even? in the Data Sufficiency forum
“Some important rules: 1. ODD +/- ODD = EVEN 2. EVEN +/- ODD = ODD 3. EVEN +/- EVEN = EVEN 4. (ODD)(ODD) = ODD 5. (ODD)(EVEN) = EVEN 6. (EVEN)(EVEN) = EVEN Target question: Is integer n EVEN? Statement 1: n² - 1 is an odd integer n² - 1 = (n + 1)(n - 1) So, statement 1 is ...”
October 1, 2018
Brent@GMATPrepNow posted a reply to When positive integer n is divided by 13, the remainder is 2 in the Problem Solving forum
“When it comes to remainders, we have a nice rule that says: If N divided by D leaves remainder R, then the possible values of N are R, R+D, R+2D, R+3D,. . . etc. For example, if k divided by 5 leaves a remainder of 1, then the possible values of k are: 1, 1+5, 1+(2)(5), 1+(3)(5), ...”
September 30, 2018
Brent@GMATPrepNow posted a reply to A marketing firm determined that, of 200 households surveyed in the Problem Solving forum
“We can also solve this question using the Double Matrix Method. Here, we have a population of 200 households , and the two characteristics are: - using or not using Brand A soap - using or not using Brand B soap So, we can set up our matrix as follows (where "~" represents ...”
September 30, 2018
Brent@GMATPrepNow posted a reply to Lindsay can paint 1/x of a certain room in 20 minutes. What in the Problem Solving forum
“Given: Lindsay can paint 1/x of a certain room in 20 minutes So, in 1 HOUR, Lindsay can paint 3/x of the room Given: Lindsay and Joseph can paint the room in 1 HOUR. During that one hour, Lindsay can paint 3/x of the room. So, during that 1 HOUR, Joseph must paint the rest (whatever Lindsay ...”
September 30, 2018
Brent@GMATPrepNow posted a reply to PS : In a certain clothing store in the Problem Solving forum
“Let C = price of one pair of the CHEAPEST socks So, 2C - 1 = price of one pair of the MOST EXPENSIVE socks A customer notices that for exactly $18, she can buy three fewer pairs of the most expensive socks than the cheapest socks. As a word equation, we can write: (# of pairs of EXPENSIVE ...”
September 30, 2018
Brent@GMATPrepNow posted a reply to If x and y are positive integers, is x/y < (x+5)/(y+5)? in the Data Sufficiency forum
“ Given: x and y are positive integers Target question: Is x/y < (x+5)/(y+5)? This is a good candidate for rephrasing the target question. Since y is POSITIVE, we can safely take the inequality x/y < (x+5)/(y+5) and multiply both sides by y. When we do this, we get: x < ...”
September 30, 2018
Brent@GMATPrepNow posted a reply to If x is the greatest common factor of 36 and 96, what is the in the Problem Solving forum
“Mitch''s solution is the approach I''d take, but another way to answer this question is to simply LIST the factors of each value and then find the GREATEST factor they have in common. When listing factors, it''s best to do so in pairs of values with a given product (either 36 or 96). Here''s what ...”
September 30, 2018
Brent@GMATPrepNow posted a reply to If a photocopier makes 2 copies in 1313 second, then, at the in the Problem Solving forum
“We can also solve this question with equivalent ratios We''ll first convert 4 minutes to SECONDS in order to use the same units of measurement throughout the solution. 1 minute = 60 seconds So, 4 minutes = 240 seconds. Now let''s set up and equation using the ratio # of copies/time in ...”
September 30, 2018
Brent@GMATPrepNow posted a reply to A number of people each wrote down one of the first 30 posit in the Data Sufficiency forum
“Target question: Were any of the integers written down by more than one of the people? Given: A number of people each wrote down one of the first 30 positive integers. Statement 1: The number of people who wrote down an integer was greater than 40. If there were exactly 30 people, ...”
September 29, 2018
Brent@GMATPrepNow posted a reply to A computer programmer needs to print 148 documents. The in the Problem Solving forum
“We can also answer this question using a step-by-step approach based on number sense. IMPORTANT: The word approximately typically suggests that we can be somewhat aggressive with our estimation There are 148 documents and the documents have an average length of 10 pages So, the TOTAL number ...”
September 29, 2018
Brent@GMATPrepNow posted a reply to List M consists of 50 decimals, each of which has a value be in the Problem Solving forum
“Let''s examine the EXTREME CASES S - T = x percent of T So, S - T = (x/100)T Divide both sides by to get: (S - T)/T = x/100 Multiply both sides by 100 to get: x = 100(S - T)/T First, we we''ll MINIMIZE the value of x by minimizing the value of S - T and maximizing the value of T. This ...”
September 29, 2018
Brent@GMATPrepNow posted a reply to If a child flips a coin five times in a row, what is the in the Problem Solving forum
“If a coin is flipped 5 times in a row, there are 32 possible outcomes (HHTTH, HTHTT, TTTTT, etc) How did we get 32? Well, there are 2 possible outcomes for the 1st coin flip, 2 possible outcomes for the 2nd coin flip, 2 outcomes for the 3rd flip, 2 outcomes for the 4th flip, and 2 outcomes for ...”
September 29, 2018
Brent@GMATPrepNow posted a reply to R and S can complete a certain job in 6 and 4 days in the Problem Solving forum
“Let''s assign a "nice" value to the job, a value that works well with the given values (6 days and 4 days ). So, let''s say the ENTIRE job is to make 24 widgets R can complete a certain job in 6 days In other words, R can make 24 widgets in 6 days So, R can make 4 widgets per day ...”
September 28, 2018
Brent@GMATPrepNow posted a reply to An engagement team consists of a project manager, team in the Problem Solving forum
“For this question, let''s first ignore the restriction regarding the two consultants who refuse to work together and find the total number of different teams. Then we''ll determine how many of those teams break the rule about the two consultants. In other words, # of "good" teams = ...”
September 28, 2018
Brent@GMATPrepNow posted a reply to In 2004, 2,400 condos sold, 15% of the total housing units in the Problem Solving forum
“We can also solve this with a little number sense If 15% of the units sold WERE condos, then 85% of the units sold new NOT condos. GIVEN: 2,400 represents 15% of the total housing units sold that year So, 4,800 must represent 30% of the total housing units sold that year And 9,600 must ...”
September 27, 2018
Brent@GMATPrepNow posted a reply to In 2004, 2,400 condos sold, 15% of the total housing units in the Problem Solving forum
“We can solve the question with equivalent ratios If 15% of the units sold WERE condos, then 85% of the units sold new NOT condos. So we want to determine the number of sold units that represent 85% of all units sold We''ll use the ratio: (number of units sold)/(percent of units sold) Let x = ...”
September 27, 2018
Brent@GMATPrepNow posted a reply to A set of numbers has an average of 50. If the largest elemen in the Problem Solving forum
“The largest element is 4 greater than 3 times the smallest element Let x = the smallest number in the set. So, 3x + 4 = the largest number in the set. So, the set looks something like this {x, ?, ?, . . . . ?, 3x+4} The key to this question is that the AVERAGE = 50 Since all of the answer ...”
September 26, 2018
Brent@GMATPrepNow posted a reply to A set of numbers has an average of 50. If the largest elemen in the Problem Solving forum
“The largest element is 4 greater than 3 times the smallest element Let x = the smallest number in the set. So, 3x + 4 = the largest number in the set. So, the set looks something like this {x, ?, ?, . . . . ?, 3x+4} The key to this question is that the AVERAGE = 50 Since all of the answer ...”
September 26, 2018
Brent@GMATPrepNow posted a reply to The sequence Sn has the terms S1=1, S2=2, S3=6, S4=15, S5=31 in the Problem Solving forum
“If you don''t spot a pattern, you can always TEST the answer choices We want to find Sn - Sn-1 So, let''s test a value of n. How about n = 2 So, we want to find the value of S2 - S1 Well, we''re told that S2 = 2 and S1 = 1 So, S2 - S1 = 2 - 1 = 1 So, when n = 2, the answer to the ...”
September 25, 2018
Brent@GMATPrepNow posted a reply to A and B represent digits in the Problem Solving forum
“I''m not saying that 68+8=86 I''m saying that, if A=6 and B=8, then our equation (AB + B = BA) becomes 68 + 8 = 86 Since this equation is faulty, we can eliminate answer choice B Cheers, Brent”
September 24, 2018
Brent@GMATPrepNow posted a reply to W, X, Y and Z each represent a different number. If the sum in the Problem Solving forum
“KEY CONCEPT: The sum of all of the rows = The sum of all of the columns So, 3 + 6 + 9 + 0 = (-2) + 7 + n + 5 Solve: n = 8 Answer: C Cheers, Brent”
September 24, 2018
Brent@GMATPrepNow posted a reply to If x^y = 1 then what is the in the Data Sufficiency forum
“Target question: What is the value of x? Given: x^y = 1 If x^y = 1, then there are 3 possible cases: case i: x = 1, and y = any value (e.g., 1^9 = 1) case ii: x = -1, and y = an even integer (e.g., (-1)^4 = 1) case iii: x = any non-zero value, and y = 0 (e.g., 7^0 = 1) Statement ...”
September 23, 2018
Brent@GMATPrepNow posted a reply to If 893 × 78 = p, which of the following is equal to 893 × in the Problem Solving forum
“Given: 893 x 78 = P 893 x 79 = 893 x (78 + 1) = (893)(78) + (893)(1) = P + 893 = D Cheers, Brent”
September 23, 2018
Brent@GMATPrepNow posted a reply to In an office that employs 120 people, m% of the employees in the Data Sufficiency forum
“I thought I''d point out that the two approaches above are known as the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it. Here, we have a population of students, and the two characteristics ...”
September 22, 2018
Brent@GMATPrepNow posted a reply to The shaded region in the figure above represents a in the Problem Solving forum
“IMPORTANT: the diagrams in GMAT problem solving questions are DRAWN TO SCALE unless stated otherwise. So, we can use this fact to solve the question by simply "eyeballing" the diagram. See our video below on this topic as well as other assumptions we can make about diagrams on the ...”
September 21, 2018
Brent@GMATPrepNow posted a reply to Challenge question: If ∆ABC is an isosceles triangle in the Data Sufficiency forum
“Target question: What is the perimeter of ∆ABC? Given: ∆ABC is an isosceles triangle Statement 1: AB = 10√3 We only know the measurement of ONE side of the triangle. So, there''s no way to determine the triangle''s perimeter. Since we cannot answer the target question with ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to Challenge question: If ∆ABC is an isosceles triangle in the Data Sufficiency forum
“Thanks Fabio! I fixed it. Cheers, Brent”
September 20, 2018
Brent@GMATPrepNow posted a reply to If Albert can travel 200 miles in 4 hours, how many hours in the Problem Solving forum
“Another approach is to apply some number sense GIVEN: Albert can travel 200 miles in 4 hours This means: Albert can travel 100 miles in 2 hours And: Albert can travel 50 miles in 1 hour 350 miles = 200 miles + 100 miles + 50 miles So, the time to travel 350 miles = 4 hours + 2 hours + 1 ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to In four years, Andy will be twice as old as Betsy. How old in the Data Sufficiency forum
“ Given: In four years, Andy will be twice as old as Betsy. Let A = Andy''s PRESENT age Let B = Betsy''s PRESENT age So, A+4 = Andy''s age IN 4 YEARS And so, B+4 = Betsy''s age IN 4 YEARS If Andy will be twice as old as Betsy IN 4 YEARS, we can write: A+4 = 2(B+4) Expand: A + 4 = 2B + 8 ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to What is the perimeter of a rectangle? in the Data Sufficiency forum
“Target question: What is the perimeter of a rectangle? This is a good candidate for rephrasing the target question. Let x = the length of the rectangle''s base Let y = the length of the rectangle''s height So, the perimeter of the rectangle = 2x + 2y REPHRASED target question: What is the ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to How many multiples of 33 lie between 101 and 1,000, inclusiv in the Problem Solving forum
“Another approach is to apply the following rule: If x and y are multiples of k, then the number of multiples of k from x to y inclusive = So, for example, the multiples of 3 from 6 to 21 inclusive = 6 So, the number of multiples of 33 from 132 to 990 inclusive = (990 - 132)/33 + 1 = 858/33 ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to How many multiples of 33 lie between 101 and 1,000, inclusiv in the Problem Solving forum
“Some positive multiples of 33 are: 33, 66, 99, 132, 165, 198,. . . , 957, 990, 1023 So, we want the number of multiples of 33 from 132 to 990 inclusive Observe: 132 = (33)(4) 165 = (33)(5) 198 = (33)(6) . . . 957 = (33)(29) 990 = (33)(30) We can see that the number of multiples of ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to Last year's receipts from the sale of candy on Valentine's in the Problem Solving forum
“GIVEN: 385 million dollars represents 7% of TOTAL candy sales In other words: 7% of TOTAL candy sales = 385 million dollars Rewrite as: (7/100)(TOTAL candy sales) = 385 million To multiply both sides by 100/7 to get: TOTAL candy sales = (100/7)(385 million) ASIDE: We need not perform any ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to In the coordinate plane, line M travels through points in the Problem Solving forum
“KEY CONCEPT: In a straight line with slope m, any segment of the line will have slope m. To get from point (9, 10) to point (0, 4), we start at (9, 10) and move 9 spaces to the left and 6 spaces down to get to (0, 4) Let''s keep going. Starting at (0, 4), we can, once again, move 9 spaces ...”
September 20, 2018
Brent@GMATPrepNow posted a reply to If x and y are different prime numbers, each greater than 2, in the Problem Solving forum
“Some important rules: #1. ODD +/- ODD = EVEN #2. ODD +/- EVEN = ODD #3. EVEN +/- EVEN = EVEN #4. (ODD)(ODD) = ODD #5. (ODD)(EVEN) = EVEN #6. (EVEN)(EVEN) = EVEN If x and y are different prime numbers, each greater than 2 . . . Since all prime numbers (EXCEPT 2) are ODD, this statement ...”
September 19, 2018
Brent@GMATPrepNow posted a reply to How many 3 digit numbers can we make such that two of the in the Problem Solving forum
“There are 3 cases to consider: case 1) numbers of the form XXY (1st and 2nd digits are the same and the 3rd digit is different) case 2) numbers of the form XYX (1st and 3rd digits are the same and the 2nd digit is different) case 3) numbers of the form YXX (2nd and 3rd digits are the same and the ...”
September 19, 2018
Brent@GMATPrepNow posted a reply to In 2001, John invest x dollars ina special account that in the Problem Solving forum
“ John $250 in his account in 2006 and in 2008 he has $270 in his account, So, in 2 years, John''s balance increases by $20 So, the balance increases $10 EACH YEAR In 2001, John invests x dollars in a special account that yields y% simple interest annually John''s balance increases $10 EACH ...”
September 19, 2018
Brent@GMATPrepNow posted a reply to GMAT Official Guide - Probability googly in the Problem Solving forum
“P(selecting a sibling pair) = P(select a junior with a sibling AND select the senior who is that junior''s sibling) = P(select a junior with a sibling) x P(select the senior who is that junior''s siblingx 1/800 = 60/800,000 = 3/40,000 = A Note: P(select a junior with a sibling) = 60/1000, ...”
September 19, 2018
Brent@GMATPrepNow posted a reply to Which of the following decribes all values of n for which in the Problem Solving forum
“Another approach is to test values and eliminate answer choices For example, one value of n that satisfies the equation n² - 1 ≥ 0 is n = 2 Notice that 2² - 1 = 4 - 1 = 3 and 3 ≥ 0 Now check the answer choices. . . Answer choice B says that n CANNOT equal 2 (since it says n ≤ 1) As ...”
September 19, 2018
Brent@GMATPrepNow posted a reply to In the figure above, what is the distance from point P to in the Problem Solving forum
“Once we create our right triangle with sides 1/2, 1/2 and x (the hypotenuse), we can apply the Pythagorean Theorem to get: (1/2)² + (1/2)² = x² Expand: 1/4 + 1/4 = x² So, 1/8 = x² This means x = √(1/8) Check the answer choices. . . .√(1/8) is not there. Looks like we need to simplify ...”
September 19, 2018
Brent@GMATPrepNow posted a reply to If six coins are flipped simultaneously, the probability of in the Problem Solving forum
“When it comes to probability questions involving "at least," it''s best to try using the complement. That is, P(Event A happening) = 1 - P(Event A not happening) So, here we get: P(getting at least one heads and at least one tails) = 1 - P(not getting at least one heads and at least one ...”
September 19, 2018
Brent@GMATPrepNow posted a reply to If n is an integer, is n(n+2) divisible by 8? in the Data Sufficiency forum
“Target question: Is n(n+2) divisible by 8? Statement 1: n is an even number. Let''s examine some CONSECUTIVE even numbers: 6, 8, 10, 12, 14, 16, 18, 20, 22, etc Notice that the numbers increase by 2 with each subsequent value. So, if n is EVEN, then we know that n+2 is also even. Also, ...”
September 19, 2018
Brent@GMATPrepNow posted a new topic called Challenge question: If ∆ABC is an isosceles triangle in the Data Sufficiency forum
“If ∆ABC is an isosceles triangle, what is the perimeter of ∆ABC? (1) AB = 10√3 (2) AC = 8 Answer: C Difficulty level: 600 - 650 Source: www.gmatprepnow.com”
September 19, 2018
Brent@GMATPrepNow posted a reply to Challenge question: If 40 percent more than 40 percent of x in the Problem Solving forum
“--------ASIDE-------------------- 40% MORE THAN k = k + (40% of k) = k + 0.4x = 1.4x 40% LESS THAN Q = Q - (40% of Q) = Q - 0.4Q = 0.6Q ----NOT ONTO THE QUESTION!!----------- 40 percent of x is the same as 0.4x So, 40 percent more than 40 percent of x is the same as (1.4)(0.4x) ...”
September 18, 2018
Brent@GMATPrepNow posted a reply to In how many ways a cricket team consisting of 5 batsmen, 4 in the Problem Solving forum
“Take the task of creating a cricket team and break it into stages. Stage 1: Select 5 batsmen Since the order in which we select the batsmen does not matter, we can use combinations. We can select 5 batsmen from 7 batsmen in 7C5 ways (21 ways) So, we can complete stage 1 in 21 ways ...”
September 18, 2018
Brent@GMATPrepNow posted a reply to Which of the following functions satisfies f(a+b)=f(a)f(b) f in the Problem Solving forum
“Another approach is to a = 1 and b = 1 So, with each function, is it true that f(1 + 1) = f(1)f(1)? In other words, is it true that f(2) = f(1)f(1)? A. f(x) = x + 1 Is it true that f(2) = f(1)f(1)? Plug values into the function to get: 2 + 1 = (1 + 1)(1 + 1) Simplify: 3 = 4 No good. ...”
September 18, 2018
Brent@GMATPrepNow posted a reply to a and b are positive numbers. What is the value of (a-b)/(a+ in the Data Sufficiency forum
“Target question: What is the value of (a - b)/(a + b)? Statement 1: a = 2b Take: (a - b)/(a + b) Replace a with 2b to get: (2b - b)/(2b + b) Simplify: b/3b Divide top and bottom by b to get: 1/3 So, the answer to the target question is (a - b)/(a + b) = 1/3 Since we can answer the ...”
September 18, 2018
Brent@GMATPrepNow posted a reply to Which of the following functions satisfies f(a+b)=f(a)f(b) f in the Problem Solving forum
“Upon scanning the answer choices, we might recognize that answer choice E, f(x) = 2^x, involves a variable exponent and that the given information that f(a+b) = f (a)f(b) looks A LOT like the Product Law: (k^a)(k^b) = k^(a+b) So, let''s check E first. E. f(x) = 2^x If f(x) = 2^x, then f(a) = ...”
September 18, 2018
Brent@GMATPrepNow posted a reply to A certain business school has a student body of 2,000 studen in the Data Sufficiency forum
“I thought I''d point out that Jay''s approach is also known as the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it. Here, we have a population of students, and the two characteristics are: ...”
September 18, 2018
Brent@GMATPrepNow posted a reply to Going in to the last game of his basketball season, Adrian in the Problem Solving forum
“Let G = total number of games that Adrian played in the ENTIRE season Going in to the last game of his basketball season, Adrian had averaged 24 points per game. At this point, Adrian has played G-1 games So, we can write: (total number of points in G-1 games)/(G-1) = 24 Multiply both sides ...”
September 17, 2018
Brent@GMATPrepNow posted a new topic called Challenge question: If 40 percent more than 40 percent of x in the Problem Solving forum
“If 40 percent more than 40 percent of x is equal to 40 percent less than y, what is the value of x/y? A) 3/8 B) 15/16 C) 1 D) 15/14 E) 15/4 Answer: D Difficulty level: 600 – 650 Source: www.gmatprepnow.com”
September 17, 2018
Brent@GMATPrepNow posted a reply to What is the perimeter of isosceles triangle LMN? 1) Side LM in the Data Sufficiency forum
“Target question: What is the perimeter of isosceles triangle LMN? Jump to. . . . Statements 1 and 2 combined There are two triangles that satisfy BOTH statements. They are: Case a: The side lengths of triangle LMN are 4, 4 and 4√2. In this case, the answer to the target question is ...”
September 17, 2018
Brent@GMATPrepNow posted a reply to 2^p/2^q=? in the Data Sufficiency forum
“Target question: What is the value of (2^p)/(2^q) ? This is a good candidate for rephrasing the target question. Aside: Here’s a video with tips on rephrasing the target question: Take: (2^p)/(2^q) Apply the Quotient law to get: 2^(p - q) This means (2^p)/(2^q) = 2^(p - q) So, in order ...”
September 17, 2018
Brent@GMATPrepNow posted a reply to Counting question in the Ask the Test Maker forum
“Good catch! (someone else just alerted me to my error) I have edited my response accordingly. Cheers, Brent”
September 17, 2018
Brent@GMATPrepNow posted a reply to If 4x − 3y = 13 and 5x + 2y = −1, then x = in the Problem Solving forum
“Given: 4x − 3y = 13 5x + 2y = −1 Take the top equation and multiply both sides by 2 Take the bottom equation and multiply both sides by 3 We get: 8x − 6y = 26 15x + 6y = −3 Add the two equations to get: 23x = 23 Solve: x = 1 Answer: C Cheers, Brent”
September 17, 2018
Brent@GMATPrepNow posted a reply to If the ratio of the present age of Anna and Paula is 3:4 in the Problem Solving forum
“Here''s a nice property of fractions: If a, b and k are positive, then (a + k)/(b + k) approaches 1 as k gets bigger. For example, the fraction (2+11)/(3+11) is closer to 1 than 2/3 is. Likewise, the fraction (1+7)/(2+7) is closer to 1 than 1/2 is. Let A = Anna''s present age Let P = Paula''s ...”
September 16, 2018
Brent@GMATPrepNow posted a new topic called If x^y = 1 then what is the in the Data Sufficiency forum
“If x^y = 1, then what is the value of x? (1) x < 0 (2) y is even integer”
September 16, 2018
Brent@GMATPrepNow posted a reply to When Leo imported a certain item, he paid a 7 percent import in the Problem Solving forum
“Here''s a step-by-step algebraic solution. Let T = the TOTAL value of the item. Leo paid a 7% import tax on the portion of the total value of the item in EXCESS of $1000 So, Leo pays tax on the amount that''s GREATER then $1000 So, Leo pays 7% tax on (T - 1000) We can write: import tax = ...”
September 16, 2018
Brent@GMATPrepNow posted a reply to A rectangular-shaped carpet remnant that measures x feet in the Problem Solving forum
“Area of rectangle = (base)(height) = (x feet)(y feet) = xy square feet GIVEN: 9 square feet = 1 square yard So, we can also say that 1 square foot = 1/9 square yards So, xy square feet = xy/9 square YARDS So, if xy/9 square YARDS cost $50, then each square YARD = $50/(xy/9) = ...”
September 16, 2018
Brent@GMATPrepNow posted a reply to Bob drives at an average rate of 50 mph from Berkeley to Los in the Problem Solving forum
“As the others have shown, the fast approach is to recognize that: travel time = distance/speed = 350/50 = 7 hours However, we could also (if necessary) solve this by applying some common sense. Bob''s speed is 50 miles per hour. In other words, for every 1 hour that elapses, Bob travels 50 ...”
September 16, 2018
Brent@GMATPrepNow posted a reply to At what speed was Erik running when he was at the halfway in the Data Sufficiency forum
“IMPORTANT: The two statements essentially provide the exact same information. If it took Erik 2 hours to travel 10 miles, we can conclude that his average speed was 5 miles per hour. When the two statements provide the same information in a Data Sufficiency question, the correct answer must be ...”
September 15, 2018
Brent@GMATPrepNow posted a reply to Probability from GMAT prep in the Problem Solving forum
“The two approaches shown above are the best (faster) approaches, but here''s one more. Since there are so few objects involved (5 apples), we should be able to quickly answer the question by simply listing and counting Let A, B, C, D, and E represent the 5 apples, and let E represent the ...”
September 15, 2018
Brent@GMATPrepNow posted a reply to A zebra must get water from either a stream or pond. Which in the Data Sufficiency forum
“Unfortunately, we don''t know if the two ''constant rates'' that are mentioned are the same OR not, so there''s no way to gauge the relative distances to the stream and pond. IF the two rates are equal, then the distances of the two water sources would be the same. [/quote] Even if the ...”
September 14, 2018
Brent@GMATPrepNow posted a reply to A zebra must get water from either a stream or pond. Which in the Data Sufficiency forum
“Target question: Which of the two sources of water is closer to the zebra’s current position? Jump straight to.... Statements 1 and 2 COMBINED There are several scenarios that satisfy BOTH statements. Here are two: Case a: When traveling to the STREAM, the zebra heads EAST in a ...”
September 14, 2018
Brent@GMATPrepNow posted a reply to Taking the GMAT in four days. Need advice calming my nerves in the GMAT Strategy forum
“You''re certainly not the first person to get nervous during this high-stakes (and expensive) test! If you''re interested, we have a free video on the topic on overcoming test anxiety: [url]http://www.gmatprepnow.com/module/general-gmat-strategies/video/1252[/url] Also, as part of managing ...”
September 14, 2018
Brent@GMATPrepNow posted a reply to If 1/n(n+1) = 1/n – 1/(n+1), then what is the value of 1/( in the Problem Solving forum
“If 1/n(n+1) = 1/n – 1/(n+1), then... 1/(1*2) = 1/1 - 1/2 1/(2*3) = 1/2 - 1/3 1/(3*4) = 1/3 - 1/4 . . . 1/(98*99) = 1/98 - 1/99 1/(99*100) = 1/99 - 1/100 So, 1/(1*2) + 1/(2*3) + 1/(3*4) + … + 1/(99*100) = (1/1 - 1/2) + (1/2 - 1/3) + (1/3 - 1/4) + . . . (1/98 - 1/99) + (1/99 - ...”
September 14, 2018
Brent@GMATPrepNow posted a reply to Is x < 0? in the Data Sufficiency forum
“Target question: Is x < 0? Statement 1: |x| = -x Let''s TEST some values. There are several values of x that satisfy statement 1. Here are two: Case a: x = -1. Notice that |-1| = -(-1). In this case, the answer to the target question is YES, x IS less than 0 Case b: x = 0. Notice that ...”
September 14, 2018
Brent@GMATPrepNow posted a reply to If n is an integer, is (n+1)^2 an even integer? in the Data Sufficiency forum
“Some important rules: 1. ODD +/- ODD = EVEN 2. ODD +/- EVEN = ODD 3. EVEN +/- EVEN = EVEN 4. (ODD)(ODD) = ODD 5. (ODD)(EVEN) = EVEN 6. (EVEN)(EVEN) = EVEN Target question: Is (n+1)² an even integer? This is a good candidate for rephrasing the target question. Aside: Here’s a video ...”
September 13, 2018
Brent@GMATPrepNow posted a reply to Jack bought five mobiles at an average price of $150. The in the Problem Solving forum
“Jack bought five mobiles at an average price of $150. So, (sum of all 5 mobiles)/5 = $150 Multiply both sides by 5 to get: sum of all 5 mobiles = $750 The median of all the prices is $200. Let a = smallest value Let b = 2nd smallest value Let d = largest value Let c = 2nd largest value ...”
September 13, 2018
Brent@GMATPrepNow posted a reply to A driver paid n dollars for auto insurance for the year in the Problem Solving forum
“First recognize that INCREASING a value by p percent is the same as multiplying by (100 + p)/100 For example, increasing a value by 7% is the same as multiplying by (100 + 7)/100 Likewise, increasing a value by 25% is the same as multiplying by (100 + 25)/100 Also, recognize that DECREASING a ...”
September 13, 2018
Brent@GMATPrepNow posted a reply to To furnish a room in a model home, an interior decorator is in the Problem Solving forum
“Total # of combinations = (# of ways to select 2 chairs)(# of ways to select 2 tables) So, 150 = (# of ways to select 2 chairs)(# of ways to select 2 tables) # of ways to select 2 chairs 5 tables, choose 2 of them. Since the order of the selected chairs does not matter, we can use ...”
September 13, 2018
Brent@GMATPrepNow posted a reply to How many positive two-digit numbers yield a remainder of 1 in the Problem Solving forum
“When it comes to remainders, we have a nice rule that says: If N divided by D leaves remainder R, then the possible values of N are R, R+D, R+2D, R+3D,. . . etc. For example, if k divided by 5 leaves a remainder of 1, then the possible values of k are: 1, 1+5, 1+(2)(5), 1+(3)(5), ...”
September 13, 2018
Brent@GMATPrepNow posted a reply to good farming (OG13 71) in the Sentence Correction forum
“(A) good growing conditions both encouraged farming traditions that, in places, endure in The word COMBINATION implies that the two conditions combine to have an effect. So, the word BOTH is redundant. ELIMINATE A (B) good growing conditions encouraged farming traditions that have, in places, ...”
September 12, 2018
Brent@GMATPrepNow posted a reply to What is the biggest positive integer which will always divid in the Problem Solving forum
“One approach is to list integers in the form n, n+1 and n+2 such that n is even, and look for a pattern... 2, 3, 4 Product = 24, which is divisible by 2, 3, 6, 12 and 24 4, 5, 6 Product = 120, which is divisible by 2, 3, 6, 12 and 24 6, 7, 8 Product = 336, which is divisible by 2, 3, 6, ...”
September 12, 2018
Brent@GMATPrepNow posted a reply to If the interior angles of a triangle are in the ratio 3 to in the Problem Solving forum
“Oops, good catch! I have edited my response accordingly. Cheers and thanks, Brent”
September 12, 2018
Brent@GMATPrepNow posted a reply to Flor is choosing three of five colors of paint to use for he in the Problem Solving forum
“Jay''s approach is the approach that I''d typically use. However, it''s important to note that, when the answer choices are so small (as they are here), we should also consider the straightforward strategy of listing and counting Let R, B, P, G and Y represent the colors Red, Blue, Purple, Green ...”
September 12, 2018
Brent@GMATPrepNow posted a reply to If the interior angles of a triangle are in the ratio 3 to in the Problem Solving forum
“All 3 angles must add to 180° So, if we divide 180° into 3 angles in the ratio 3 : 4 : 5, we get: 45° : 60° : 75° What is the measure of the largest angle? The largest angle is 75 degrees° Answer: D Cheers, Brent”
September 12, 2018
Brent@GMATPrepNow posted a reply to Is p + pz = p? in the Data Sufficiency forum
“Target question: Is p + pz = p? This is a great candidate for rephrasing the target question. Aside: Here’s a video with tips on rephrasing the target question: Take Is p + pz = p? and subtract p from both sides to get: Is pz = 0? In order for pz to equal 0, it must be the case that ...”
September 12, 2018
Brent@GMATPrepNow posted a reply to A company plans to assign identification numbers to its in the Problem Solving forum
“Take the task of creating the identification numbers and break it into stages. Stage 1: Select the first digit of the identification number The first digit can be 1, 2, 3, 4, 5, 6, 7, 8, or 9 So, we can complete stage 1 in 9 ways Stage 2: Select the second digit of the identification ...”
September 12, 2018
Brent@GMATPrepNow posted a reply to Last week Chris earned x dollars per hour for the first 40 in the Problem Solving forum
“If Chris worked 48 hours, then he was paid 40x dollars for first 40 hours and (8)(22) dollars for the next 8 hours Since Chris earned $816, we can write: 40x + (8)(22) = 816 Simplify: 40x + 176 = 816 Subtract 176 from both sides: 40x = 640 Solve: x = 640/40 = 16 Answer: D Cheers, Brent”
September 11, 2018
Brent@GMATPrepNow posted a reply to If x is even integer, which of the following must be an odd in the Problem Solving forum
“A quick approach is the plug in a even number for x and see what happens. A super easy number to use us x = 0 We get..... A) (3)(0)/2 = 0, which is NOT odd. ELIMINATE A. B) (3)(0)/2 + 1 = 1, which IS odd. KEEP B. C) (3)(0)² = 0, which is NOT odd. ELIMINATE C. D) (3)(0²)/2 = 0, which ...”
September 11, 2018
Brent@GMATPrepNow posted a reply to The perimeter of a rectangular garden is 360 ft. What is the in the Data Sufficiency forum
“Great research, Mitch! I can''t imagine there are many official questions that hinge entirely on that one (somewhat esoteric) construct. I mean, for the every question you cited, it doesn''t matter which side we call the length or the width. The correct answer is the same in all cases. It''s ...”
September 11, 2018
Brent@GMATPrepNow posted a reply to The perimeter of a rectangular garden is 360 ft. What is the in the Data Sufficiency forum
“Interesting. I''ve never heard of that construct. So, for a box with dimensions 3 x 4 x 5, then the side with length 5 is the length? Which dimension is the width? What about cases when the terms base and height are used? Which one is the base? In a way, this reminds me of the times when ...”
September 11, 2018
Brent@GMATPrepNow posted a reply to The aerth travels around the sun at a speed of approximately in the Problem Solving forum
“Another way to deal with calculating (18.5)(3600) is to use the answer choices to our advantage. First off, there''s a nice rule that says: AB = (2A)(0.5B) This strategy (which is covered in this video: https://www.gmatprepnow.com/module/general-gmat-strategies/video/1113) can sometimes save us ...”
September 11, 2018
Brent@GMATPrepNow posted a reply to What is the value of 22C19? in the Problem Solving forum
“Good point! I should have mentioned that I use a shortcut for calculating combinations that allows me to perform most calculations in my head. For example, for 22C3, I write the first 3 values of 22! in the numerator, and I write the 3! in the denominator So, 22C3 = (22)(21)(20)/(3)(2)(1) ...”
September 11, 2018
Brent@GMATPrepNow posted a reply to What is the value of 22C19? in the Problem Solving forum
“When calculating combinations, it''s sometime useful to apply the following rule: nCr = nC(n-r). In other words, "n choose r" is equal to "n choose n - r" So, for example: 10C7 = 10C3 12C9 = 12C3 8C7 = 8C1 etc. Here''s why this property works: Let''s say you have 22 ...”
September 11, 2018
Brent@GMATPrepNow posted a reply to The perimeter of a rectangular garden is 360 ft. What is the in the Data Sufficiency forum
“To my test-prep colleagues. I have to say that I''m a little surprised by the official answer (D). For statement 2, it could be the case that length = 120 and width = 60, OR it could be the case that length = 60 and width = 120 The assumption here is that the length of a rectangle must be ...”
September 11, 2018
Brent@GMATPrepNow posted a reply to Which of the following points could lie in the same quadrant in the Problem Solving forum
“Let''s test some coordinates... How about: a = 1 and b = -2. This means the point (a, b) = (1, -2), which is in QUADRANT IV Now plug a = 1 and b = -2 into each answer choice... A) (-b, -a) = -2), -1] = (2, -1), which is also in QUADRANT IV PERFECT! Answer: A Cheers, Brent”
September 11, 2018
September 10, 2018
Brent@GMATPrepNow posted a reply to The sum of the ages of Doris and Fred is y years. If Doris in the Problem Solving forum
“Let F = Fred''s PRESENT age Doris is 12 years older than Fred. In other words, Doris'' age = F + 12. So, the sum of their ages = F + (F + 12) Simplify to get: sum of their ages = 2F + 12 The sum of the ages = y 2F + 12 = y Now solve for Fred''s age (F). Start with: 2F + 12 = y ...”
September 10, 2018
Brent@GMATPrepNow posted a reply to In the figure, ABCD is a square, and all the dots are in the Problem Solving forum
“If the vertical or horizontal distance between two adjacent dots is 3 units, then the square has dimensions 12 by 12 So, the area of the ENTIRE SQUARE = (12)(12) = 144 Now, notice that the square is comprised of 32 identical triangles https://i.imgur.com/mHC9rOY.png Since 16 of the triangles ...”
September 10, 2018
Brent@GMATPrepNow posted a reply to Is xy>0? in the Data Sufficiency forum
“Target question: Is xy > 0? Statement 1: x³y > 0 Since x² is POSITIVE, we can safely divide both sides of the inequality by x² When we do this, we get xy > 0 So, the answer to the target question is YES, xy IS greater than 0 Since we can answer the target question with ...”
September 10, 2018
Brent@GMATPrepNow posted a reply to If the circle above has center O and circumference 18π, the in the Problem Solving forum
“The circle has circumference 18π circumference = (2)(radius)(π) So, (2)(radius)(π) = 18π Solve to get: radius = 9 So, OR = 9 and OT = 9 Now, we''ll deal with arc RST Here the sector angle = 60° 60°/360° = 1/6 So, the arc RST represents 1/6 of the ENTIRE circle Since the ENTIRE ...”
September 10, 2018
Brent@GMATPrepNow posted a reply to Any decimal that has only a finite number of nonzero digits in the Data Sufficiency forum
“Target question: Is r/s a terminating decimal? Statement 1: 90 < r < 100 There are several pairs of values that meet this condition. Here are two: Case a: r = 91 and s = 2, in which case r/s = 91/2 = 45.5 = a terminating decimal Case b: r = 91 and s = 3, in which case r/s = 91/3 = ...”
September 10, 2018
Brent@GMATPrepNow posted a reply to In a certain pond, 50 fish were caught, tagged, and returned in the Problem Solving forum
“We can use equivalent ratios here. We''re told that the proportion of tagged fish in the 50-fish SAMPLE is equal to the the proportion of tagged fish in the ENTIRE pond. So, (# tagged fish in SAMPLE)/50 = (total # tagged fish)/(total # of fish in POND) Let x = # of fish in the entire ...”
September 10, 2018
Brent@GMATPrepNow posted a reply to permutation/combination in the Problem Solving forum
“This question is a little too ambiguous to be an official GMAT question. Let''s say X, Y and Z represents 3 different songs. Is an album with song X first, song Y second and song Z third considered DIFFERENT FROM an album with song Z first, song X second and song Y third? The answer to this ...”
September 9, 2018
Brent@GMATPrepNow posted a reply to Sam's car was fined when he gave Joe and Peter a ride, so in the Problem Solving forum
“Hey Mitch, I think you answered the question "What was the cost of the fine?" (which IS, indeed, $48), but we''re asked to determine the dollar amount that Sam paid (= $20). Cheers, Brent”
September 9, 2018
Brent@GMATPrepNow posted a reply to On Monday morning a certain machine ran continuously at a un in the Data Sufficiency forum
“Here''s a similar question to practice with: https://www.beatthegmat.com/on-wednesday-morning-a-fortune-cookie-machine-ran-t301683.html Cheers, Brent”
September 9, 2018
Brent@GMATPrepNow posted a reply to Sam's car was fined when he gave Joe and Peter a ride, so in the Problem Solving forum
“Let F = the total cost of the fine Joe paid $3 more than 1/4 of the fine So, F/4 + 3 = the amount Joe paid Peter paid $3 less than 1/3 of the fine So, F/3 - 3 = the amount Peter paid Sam paid $4 less than 1/2 the fine So, F/2 - 4 = the amount Sam paid (amount Joe paid) + (amount Peter ...”
September 8, 2018
Brent@GMATPrepNow posted a reply to What is the area of a triangle with the following vertices in the Problem Solving forum
“Now that you know the technique, you can practice your speed with this one: http://www.beatthegmat.com/coordinate-geometry-t116975.html Cheers, Brent”
September 8, 2018
Brent@GMATPrepNow posted a reply to In the xy-plane, the line k passes through the origin and in the Data Sufficiency forum
“Target question: Is b (the y-coordinate of the point on the line) positive? Given: Line k passes through the origin and through the point (a,b) Statement 1: The slope of line k is negative There are several lines and points that satisfy statement 1. Here are two: Case a: ...”
September 8, 2018
Brent@GMATPrepNow posted a reply to Out of 2 broken TV sets and 6 fixed TV sets in Joe's Fix-My- in the Problem Solving forum
“There are 8 TV''s in total 2 are broken 6 are fixed We want to find P(at least one TV is broken) When it comes to probability questions involving at least, it''s often best to try using the complement. That is, P(Event A happening) = 1 - P(Event A not happening) So, here we get: P(getting ...”
September 8, 2018
Brent@GMATPrepNow posted a reply to what percent were stockholders who were not employees? in the Problem Solving forum
“Let''s use the Double Matrix Method. This technique can be used for most questions featuring a population in which each member has two characteristics associated with it (aka overlapping sets questions). Here, we have a population of attendees, and the two characteristics are: - stockholder ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to Geometry and Angles (My weakness) in the Problem Solving forum
“Here''s an idea of what''s going on.... https://i.imgur.com/Deg4te0.png When we compare the big triangle with the BASE 30-60-90 special triangle (which you must memorize for test day!), we can see that the hypotenuse of the big triangle is 35 times as long as the hypotenuse of the base triangle. ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to Digging in sediments in northern China, evidence has been in the Sentence Correction forum
“Important: When a sentence begins with a with noun modifier (as it does in the above sentence), stop at the comma and ask the question that the modifier raises. So, once we read, Digging in sediments in northern China, we should stop and ask . . . "Who or what was digging in ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to OG City Council Member Q in the Critical Reasoning forum
“PREMISE: Electricity demands increase 1.5% per year PREMISE: No space to build more power plants CONCLUSION: We must use LESS electricity through ordinances Strategy #1: Try to think of an assumption that''s required for the conclusion to logically follow from the premises. Notice that ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to Working simultaneously and independently at an identical con in the Problem Solving forum
“Let''s assign a nice value to x (a value that will work well with all of the numbers 3, 4 and 6. Let''s say x = 24 GIVEN: 4 machines make x units in 6 days This means 4 machines make 24 units in 6 days So, 4 machines make 4 units in 1 day So, 1 machine makes 1 unit in 1 day From here, ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to What is the value of the 2-digit positive integer n if its in the Data Sufficiency forum
“Target question: What is the value of the 2-digit positive integer n Given: Its tens digit is four times its units digit This is VERY LIMITING information. In fact, this tells us that EITHER n = 41 OR n = 82 There are no other possible values of n. Statement 1: n is an even number ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to A refrigerator holds a number of apples, bananas, carrots an in the Data Sufficiency forum
“Be careful. If you feel that the ratio A : B : C : D = 2x : 5x : 3x : 7x, then you''d be able to answer the target question WITHOUT using any statements. Cheers, Brent”
September 7, 2018
Brent@GMATPrepNow posted a reply to Which of the following points is the intersection between in the Problem Solving forum
“KEY CONCEPT: The point of intersection (call P) of the lines y = 3x + 6 and y = -2x - 4 will be such that the x- and y-coordinates of P will satisfy BOTH equations. Since both equations are set equal to y, we can write: 3x + 6 = -2x - 4 Add 2x to both sides: 5x + 6 = - 4 Subtract 6 from both ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to If a mixture of ground meat consists of 2 pounds of veal in the Problem Solving forum
“We can use the WEIGHTED AVERAGE formula: Weighted average of groups combined = (group A proportion)(group A average) + (group B proportion)(group B average) + (group C proportion)(group C average) + ... When we COMBINE the meats, the TOTAL weight = 2 + 5 = 7 pounds. So, veal comprises 2/7 of ...”
September 7, 2018
Brent@GMATPrepNow posted a reply to Last year the price per share of Stock X increased by k in the Problem Solving forum
“One approach is to plug in values. Let $100 be the original price per share of Stock X Choose a "nice" value for k. How about k = 200 So, after a 200% increase, the new price per share = $300 Let $100 be the original earnings per share of Stock X Choose a "nice" ...”
September 6, 2018
Brent@GMATPrepNow posted a reply to If 3x + 2y = -2z, what is x? in the Data Sufficiency forum
“Target question: What is the value of x? Given: 3x + 2y = -2z Notice that the two statements have the variables all on the left side of the equation. So, let''s rearrange our given equation to look the same. Take: 3x + 2y = -2z Add 2z to both sides to get: 3x + 2y + 2z = 0 Statement ...”
September 6, 2018
Brent@GMATPrepNow posted a reply to The selling price of an article is equal to the cost of the in the Data Sufficiency forum
“Let C = cost of article Target question: The markup on a certain television set is what percent of the selling price? Statement 1: The markup on the television set is 25 percent of the cost. If C = cost of article, markup = 0.25C Selling price = cost + markup = C + 0.25C = 1.25C So, ...”
September 6, 2018
Brent@GMATPrepNow posted a reply to Last year, a certain public transportation system sold an in the Problem Solving forum
“The word "closest" suggests that we can use some estimation here. Let''s first estimate the number of tickets sold PER WEEK 41,000 tickets per day on weekdays (5)(41,000) = 205,000 18,000 tickets per day on weekends (2)(18,000) = 36,000 So, total tickets sold PER WEEK = ...”
September 5, 2018
Brent@GMATPrepNow posted a reply to In the xy-coordinate system, line k has slope 1/2 and passes in the Problem Solving forum
“While a sample size of 28 might not be a large enough to make prove/validate my recommendations, I can tell you that, from my experience, the correct answer to these kinds of questions is typically closer to E than to A. That said, if it were the case that, with this question type, the correct ...”
September 5, 2018
Brent@GMATPrepNow posted a reply to In the figure above, what is the perimeter of rectangle ABPQ in the Data Sufficiency forum
“Target question: What is the perimeter of rectangle ABPQ? Statement 1: The area of rectangular region ABCD is 3 times the area of rectangular region ABPQ. Since we aren''t given any information regarding ACTUAL lengths, we cannot determine the perimeter of rectangle ABPQ Since we cannot ...”
September 5, 2018
Brent@GMATPrepNow posted a reply to The numbers x and y are NOT integers. The value of x is in the Data Sufficiency forum
“Target question: The value of x is closest to which integer? Let''s head straight to........... Statements 1 and 2 combined There are several values of x and y that satisfy BOTH statements. Here are two: Case a: x = 2.4 and y = 1.4. These values satisfy both statements. In this case, ...”
September 5, 2018
Brent@GMATPrepNow posted a reply to An insurance company sells only one type of health and one in the Data Sufficiency forum
“Let H = the number of health insurance policies Let L = the number of life insurance policies Let p = the monthly premium on a life insurance policy So, 80H + pL = 5000 Target question: What is the value of p? Statement 1: The total revenue from health insurance premiums was 4/5 of ...”
September 5, 2018
Brent@GMATPrepNow posted a reply to 8 cities, including Memphis, are finalists to be chosen to in the Data Sufficiency forum
“Target question: What is the probability that Memphis is not chosen? ASIDE: At first glance, it may seem like we already have enough information the answer the target question. After all, if there are 8 cities, then P(Memphis is chosen) = 1/8, which means Memphis is not chosen) = 7/8, right? ...”
September 5, 2018
Brent@GMATPrepNow posted a reply to In the xy-coordinate system, line k has slope 1/2 and passes in the Problem Solving forum
“Let''s first determine the equation of line k A quick approach is the write the equation of line k in slope y-intercept form: y = mx + b, where m = slope and b = y-intercept. We''re told that the slope = 0.5 and the point (0,5) tells us that the y-intercept is 5 So, the equation of line k is: ...”
September 5, 2018
Brent@GMATPrepNow posted a reply to A certain company assigns employees to offices in such a way in the Problem Solving forum
“ASIDE: When the answer choices are small, you should also consider listing and counting Let X, Y and Z be the 3 employees. Let A and B be the 2 offices. We''ll list the possible outcomes as follows: (employees in office A | employees in office B) So, we get: ( XYZ | -- ) ( XY |Z ) ( XZ ...”
September 5, 2018
Brent@GMATPrepNow posted a reply to A certain company assigns employees to offices in such a way in the Problem Solving forum
“Let X, Y and Z be the 3 employees. Let A and B be the 2 offices. Take the task of assigning the employees and break it into stages. Stage 1: Assign employee X to an office There two options (office A or office B), so we can complete stage 1 in 2 ways Stage 2: Assign employee Y to an ...”
September 5, 2018
Brent@GMATPrepNow posted a reply to A baker makes chocolate cookies and peanut cookies. His in the Problem Solving forum
“We''re looking for the smallest possible number of chocolate chip cookies. So, let''s start by testing answer choice A A) If we make 7 chocolate chip cookies, then the remaining 88 cookies are peanut cookies. We''re told that peanut cookies are baked in batches of 6 However, 88 is NOT ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to If x and y are integers, what is the least possible positive in the Problem Solving forum
“Another approach: There''s a nice rule that says: If j, k and d are integers, and j is a multiple of d, and k is a multiple of d, then (j+k) must be a multiple of d 21x is a multiple of 7 (since 21x = 7(3x) 35y is a multiple of 7 (since 35y = 7(5y) Since 21x and 35y are multiples of 7, the ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to If x and y are integers, what is the least possible positive in the Problem Solving forum
“21x + 35y = 7(3x + 5y) Since x and y are INTEGERS, we know that 3x and 5y are each INTEGERS, which means 3x + 5y equals some integer So, we can write: 21x + 35y = 7(some integer) In other words, 21x + 35y is a multiple of 7 Check the answer choices.....only D is a multiple of 7 Answer: D ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to standard deviation in the Data Sufficiency forum
“Target question: Is the standard deviation of the set positive? KEY CONCEPT: If all of the numbers in a set are EQUAL, then the standard deviation = 0 If the numbers in a set are NOT all equal, then the standard deviation > 0 Given: The set consists of a certain number of even integers ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to permutation/combination in the Problem Solving forum
“Here''s an algebraic solution... Let M = TOTAL number of men (including Mr. Smith) at the party Let W = TOTAL number of women (including Mrs. Smith) at the party Since Mr. Smith does not shake hands with HIMSELF, Mr. Smith shakes hands with M-1 men, and he shakes hands with W women Since ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to Andrew has a certain number of coins in his pocket. He has in the Problem Solving forum
“Let x = number of QUARTERS in pocket So, 0.25x = VALUE of quarters in pocket He has three times as many dimes as quarters So, 3x = number of DIMES in pocket So, 0.10(3x) = 0.3x = VALUE of dimes in pocket He has six times as many nickels as dimes. So, (6)(3x) = number of NICKELS in ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to Triathlete Dan runs along a 2-mile stretch of river and then in the Problem Solving forum
“Average speed = (total distance)/(total time) We know the total distance = 4 miles The total time consists of two parts: Let''s begin with a "word equation" TOTAL time = (time spent running) + (time spent swimming) time = distance/speed So, time spent running = 2/10 = 1/5 hours ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to At a garage sale, all of the prices of the items sold were in the Problem Solving forum
“The price of the radio was the 15th highest price So, there were 14 items that were more expensive than the radio. In other words, if we listed all of the prices in ascending order, we''d get something like: ........... radio, X, X, X, X, X, X, X, X, X, X, X, X, X, X The price of the radio ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to The average television prime-time advertising unit of 30 in the Problem Solving forum
“We can also quickly solve this question by testing the answer choices.... Start with C (40%) 40% of $30,000 = $12,000 So, a 40% increase (from 1973 to 1977) = $30,000 + $12000 = $42,000 No good. We need to new amount to be $50,000 ELIMINATE C Since $42,000 is less than $50,000, we need a ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to Each of the following numbers has a remaider of 2 when in the Problem Solving forum
“ASIDE: This is one of those questions that require us to check/test each answer choice. In these situations, always check the answer choices from E to A, because the correct answer is typically closer to the bottom than to the top. For more on this strategy, see my article: ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to At a certain hospital, 75% of the interns receive fewer than in the Problem Solving forum
“I thought I''d point out that Mitch''s Double Matrix approach can be used for most questions featuring a population in which each member has two characteristics associated with it. Here, we have a population of interns, and the two characteristics are: - less than 6 hours sleep or 6 or more ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to DS_Arithmetic in the Data Sufficiency forum
“Target question: What is the tenth digit in the decimal representation of a certain number? Jump straight to..... Statements 1 and 2 combined Statement 1 tells us that the number is less than 1/3 (aka 0.333333....) Statement 2 tells us that the number is greater than 1/4 (aka 0.25) ...”
September 4, 2018
Brent@GMATPrepNow posted a reply to permutation/combination in the Problem Solving forum
“This question is a little too ambiguous to be a true (official) GMAT question. Does order matter here? For example, is E driving, A in passenger seat, G in middle of back seat, and C in left side of back seat DIFFERENT FROM C driving, A in passenger seat, E in middle of back seat, and G in left ...”
September 3, 2018
Brent@GMATPrepNow posted a reply to A store sold 6 bicycles with an average sale price of $1,000 in the Data Sufficiency forum
“Target question: What was the price of the most expensive bicycle? Given: The store sold 6 bicycles with an average sale price of $1,000. This means the SUM of the 6 bikes = $6000 (since $6000/6 bikes = $1000 average) Statement 1: The median price was $1,000. This statement doesn''t ...”
September 3, 2018
Brent@GMATPrepNow posted a reply to Alex paid a $12 fee to receive a 10% discount off of the in the Problem Solving forum
“IMPORTANT: If Alex received a 10% discount, then Alex PAID 90% of the cost of the books If Victor received a 15% discount, then Victor PAID 85% of the cost of the books Start with a word equation Total amount Alex paid = Total amount Victor paid We get: $12 + 90% of b = $15 + 85% of b ...”
September 3, 2018
Brent@GMATPrepNow posted a reply to Paula and Sandy were among those people who sold raffle in the Data Sufficiency forum
“Target question: How many of the tickets did Paula sell? Given: Paula and Sandy sold a total of 100 of the tickets Let x = number of tickets that Paula sold This means 100-x = number of tickets that Sandy sold Statement 1: Sandy sold 2/3 as many of the raffle tickets as Paula did. We ...”
September 3, 2018
Brent@GMATPrepNow posted a reply to Six children — A, B, C, D, E, and F — are going to sit i in the Problem Solving forum
“Here are a few similar questions to practice with: - http://www.beatthegmat.com/permutation-t261691.html - http://www.beatthegmat.com/vowels-and-consonants-arrangement-t149946.html - http://www.beatthegmat.com/how-many-possible-orders-t277574.html Cheers, Brent”
September 3, 2018
Brent@GMATPrepNow posted a reply to integers in the Problem Solving forum
“Here''s one way to look at it. Write all of the numbers as 3-digit numbers. That is, 000, 001, 002, 003, .... 998, 999 NOTE: Yes, I have started at 000 and ended at 999, even though though the question asks us to look at the numbers from 1 to 1000. HOWEVER, notice that 000 and 1000 do not ...”
September 1, 2018
Brent@GMATPrepNow posted a reply to How many positive integers less than 2*10^4 are there in in the Problem Solving forum
“In other words, "How many positive integers less than 20,000 are there in which each digit is a prime number?" The prime digits are: 2, 3, 5 and 7 Notice that, using the digits 2, 3, 5 and 7, we cannot create a 5-digit number that''s less than 20,000 So, we must consider 4 possible ...”
September 1, 2018
Brent@GMATPrepNow posted a reply to Each baseball team in a league has a roster of players in in the Problem Solving forum
“There are 2 pitchers for every 3 fielders So, out of every 5 players, there are 2 pitchers. So, in ONE 25-player team, there are 10 pitchers (and 15 fielders) So, if there are 12 teams, and there are 10 pitchers and 15 fielders per team, then... TOTAL number of pitchers = (12)(10 ) TOTAL ...”
September 1, 2018
Brent@GMATPrepNow posted a reply to Which of the following are/is prime? in the Problem Solving forum
“I. 143 143 = (11)(13) Since 143 is NOT prime, we can ELIMINATE C, D and E II. 147 Notice that 147 = 140 + 7 Since 140 is divisible by 7, and 7 is divisible by 7, we know that 147 is divisible by 7. Since 147 is NOT prime, we can ELIMINATE A So, the answer (by the process of elimination) ...”
September 1, 2018
Brent@GMATPrepNow posted a reply to A certain library assesses fines for overdue books as in the Problem Solving forum
“1st day - $0.10 2nd day - $0.20 or $0.40 (double or add $0.30) $0.20 is the lesser amount 3rd day - $0.40 or $0.50 (double or add $0.30) $0.40 is the lesser amount 4th day - $0.80 or $0.70 (double or add $0.30) $0.70 is the lesser amount The correct answer is B Cheers, Brent”
August 31, 2018
Brent@GMATPrepNow posted a reply to The Hazelton coal-processing plant is a major employer in in the Critical Reasoning forum
“PREMISE: Coal plant will be shut down it it doesn''t upgrade PREMISE: Expensive upgrade will force company to close, UNLESS it receives tax break PREMISE: To PREVENT increase in local unemployment, government may grant tax break IMPORTANT: the government''s goal is to PREVENT an increase in ...”
August 30, 2018
Brent@GMATPrepNow posted a reply to Angela has 15 pairs of matched socks. If she loses 7 in the Problem Solving forum
“We can also systematically eliminate 4 of the 5 answer choices. Let''s say the 15 PAIRS of socks are as follows: AA, BB, CC, DD, EE, FF, GG, HH, II, JJ, KK, LL, MM, NN, OO Let''s first see what happens if we "lose" 7 unmatched socks. Say, we lose, A, B, C, D, E, F, G We get: A, B, ...”
August 30, 2018
Brent@GMATPrepNow posted a reply to What is the range of 10 numbers? in the Data Sufficiency forum
“Target question: What is the range of 10 numbers? Statement 1: The average (arithmetic mean) of the 10 numbers is 10 Let''s TEST some values. There are several sets of numbers that satisfy statement 1. Here are two: Case a: the numbers are {10, 10, 10, 10, 10, 10, 10, 10, 10, 10}. In this ...”
August 30, 2018
Brent@GMATPrepNow posted a reply to A jar contains 16 red balls and 8 white balls. If 3 balls ar in the Problem Solving forum
“There are 24 balls in the jar (before any are removed) P(all 3 balls are white) = P(1st ball is white AND 2nd ball is white AND 3rd ball is white) = P(1st ball is white) x P(2nd ball is white) x P(3rd ball is white) = 8/24 x 7/23 x 6/22 = 1/3 x 7/23 x 3/11 = 7/253 ASIDE: rather than ...”
August 30, 2018
Brent@GMATPrepNow posted a reply to Pumping alone at their respective constant rates, one inlet in the Problem Solving forum
“Let''s assign a nice value to the volume of the tank. We want a volume that works well with the given information (1/2, 2/3, 3 hours and 6 hours). So, let''s say the tank has a total volume of 18 gallons One inlet pipe fills an empty tank to 1/2 of capacity in 3 hours 1/2 the tank is 9 ...”
August 30, 2018
Brent@GMATPrepNow posted a reply to At a constant rate of flow, it take 20 minutes to fill a in the Problem Solving forum
“Let''s assign a nice value to the volume of the pool. We want a volume that works well with the given information (20 minutes and 30 minutes). So, let''s say the pool has a total volume of 60 gallons It takes 20 minutes to fill a swimming pool with a LARGE hose In other words, the LARGE hose ...”
August 30, 2018
Brent@GMATPrepNow posted a reply to If 4 is one solution of the equation x^2 + 3x + k = 10, in the Problem Solving forum
“Let''s first determine the value of k. Since x = 4 is a solution to the equation x² + 3x + k = 10, we know that x = 4 SATISFIES the equation. That is: 4² + 3(4) + k = 10 Evaluate to get: 16 + 12 + k = 10 Solve for k to get: k = -18 So, the ORIGINAL equation is x² + 3x + (-18) = 10 ...”
August 30, 2018
Brent@GMATPrepNow posted a reply to In a certain summer school program, there are five periods in the Problem Solving forum
“Take the Science, and Science Lab classes and "glue" them together to get the super class "Science-Science-Lab" This ensures that Science Lab immediately follows the Science class So, we now have only 4 classes: English, Math, History and Science-Science-Lab We can arrange ...”
August 29, 2018
Brent@GMATPrepNow posted a reply to Is the measure of one of the interior angles of in the Data Sufficiency forum
“Target question: Is the measure of one of the interior angles of quadrilateral ABCD equal to 60? Key concept: the 4 angles in a quadrilateral must add to 360 degrees Statement 1: Two of the interior angles of ABCD are right angles. Let''s test some possible cases. There are infinitely ...”
August 28, 2018
Brent@GMATPrepNow posted a reply to Solution X, which is 50% alcohol, is combined with solution in the Problem Solving forum
“When solving mixture questions, I find it useful to sketch the solutions with the ingredients SEPARATED: https://i.imgur.com/X6UPop8.png Since we want to determine the volume of solution Y needed, let''s... ...let y = volume (in liters) of solution Y needed This means 16 - y = volume (in ...”
August 28, 2018
Brent@GMATPrepNow posted a reply to Is xy>0? in the Data Sufficiency forum
“Target question: Is xy>0? Statement 1: x + y > 0 This statement doesn''t FEEL sufficient, so I''ll TEST some values. There are several values of x and y that satisfy statement 1. Here are two: Case a: x = 1 and y = 1. In this case, xy = (1)(1) = 1. So, the answer to the target ...”
August 28, 2018
Brent@GMATPrepNow posted a reply to When traveling at a constant speed of 32 miles per hour, a in the Problem Solving forum
“Let''s see what happens after ONE HOUR of traveling. In ONE hour, the boat will travel 32 miles and will use 24 gallons of fuel So, the fuel consumption rate is 32 miles per 24 gallons Or we can write: fuel consumption rate = 32/24 miles/gallon 32/24 = 4/3 So, the fuel consumption rate = ...”
August 28, 2018
Brent@GMATPrepNow posted a reply to Exactly 8 years ago, Jim's son was twice as old as Jim's in the Problem Solving forum
“Jim’s son is now 5 years older than his daughter Let D = the daughter''s age NOW So D + 5 = the son''s age NOW This also means that D - 8 = the daughter''s age EIGHT YEARS AGO This also means that D + 5 - 8 = the son''s age EIGHT YEARS AGO Or we can say, D - 3 = the son''s age EIGHT YEARS ...”
August 28, 2018
Brent@GMATPrepNow posted a reply to What is the sum of all multiples of 3 between 1 and 200? in the Problem Solving forum
“Useful formula: 1 + 2 + 3 + 4 + . . . n = (n)(n + 1)/2 We want to find the sum: 3 + 6 + 9 + 12 + . . . 198 Factor out the 3 to get: 3(1 + 2 + 3 + 4 + . . . 66) Apply formula to get: 3(66)(67)/2 Evaluate to get: 6633 Answer: C Cheers, Brent”
August 28, 2018
Brent@GMATPrepNow posted a reply to What is the value of x? in the Data Sufficiency forum
“Here''s another way to look at it..... (1) 310x + 562y = 909 We can think of this as the equation of a line. The x- and y-coordinates of all points on the line will satisfy the equation 310x + 562y = 909 Since there are infinitely many points on the line, there are infinitely many possible ...”
August 27, 2018
Brent@GMATPrepNow posted a reply to George bought a large electronic item with a 15% off coupon, in the Problem Solving forum
“George was SUPPOSED to receive a 15% discount, but he received a 30% discount. So, he should have returned 15% of the original cost. However, the manager asked for half that amount (i.e., 7.5% of the original cost) In other words, 7.5% of the original cost = $40.50 IMPORTANT: at this point, ...”
August 27, 2018
Brent@GMATPrepNow posted a reply to GMAT Prep Problem 3 in the Problem Solving forum
“Here''s the complete question: Let''s first determine the least possible integer. We''ll use the answer choices to help us along... A) Could the smallest value on the card be 3? Well, the next larger integer is 4, and 3 x 4 = 12, which is OUTSIDE the given range of 15 to 200 So, we ...”
August 27, 2018
Brent@GMATPrepNow posted a reply to GMAT Prep Problem 1 in the Problem Solving forum
“Here''s another algebraic approach. Let M = Alice''s monthly take home pay Let f = the fraction we''ll use to calculate monthly savings The means that fM = the amount of $ Alice saves each month. And this means that her annual savings = 12fM Important: If f = the fraction used to ...”
August 27, 2018
Brent@GMATPrepNow posted a reply to If m and n are integers greater than 1, is m^n>500? in the Data Sufficiency forum
“Target question: Is m^n > 500? Given: m and n are integers greater than 1 Statement 1: n > 8 We''re told that m and n are integers greater than 1 So, the SMALLEST possible value of m is 2 And, if n > 8, the SMALLEST possible value of n is 9 When we plug in these SMALLEST ...”
August 27, 2018
Brent@GMATPrepNow posted a reply to If x and y are positive integers and xy=36, what is the smal in the Problem Solving forum
“Since there aren''t many PAIRS of integers that have a product of 36, we can simply list the possibilities: x = 1 and y = 36. Here, the SUM = 37 x = 2 and y = 18. Here, the SUM = 20 x = 3 and y = 12. Here, the SUM = 15 x = 4 and y = 9. Here, the SUM = 13 x = 6 and y = 6. Here, the SUM = 12 ...”
August 27, 2018
Brent@GMATPrepNow posted a reply to For which of the following functions is f(a+b) = F(a) + f(b) in the Problem Solving forum
“One approach is to plug in numbers. Let''s let a = 1 and b = 1 So, the question becomes, "Which of the following functions are such that f(1+1) = f(1) + f(1)?" In other words, for which function does f(2) = f(1) + f(1)? A) If f(x)=x², does f(2) = f(1) + f(1)? Plug in to get: 2² ...”
August 27, 2018
Brent@GMATPrepNow posted a reply to If n = 10^10 and n^n = 10^d, what is the value of d? A. 10^ in the Problem Solving forum
“A slightly different approach.... Given: n = 10^10 Also given: n^n = 10^d Replace n in the base with 10^10 to get: (10^10)^n = 10^d Apply Power of a Power rule on left side to get: 10^10n = 10^d So, we can conclude that 10n = d Now replace the remaining n with 10^10 to get: 10(10^10) = d ...”
August 26, 2018
Brent@GMATPrepNow posted a reply to If it takes Jacob x hours to complete a project and it in the Problem Solving forum
“For work questions, there are two useful rules: Rule #1: If a person can complete an entire job in k hours, then in one hour, the person can complete 1/k of the job Example: If it takes Sue 5 hours to complete a job, then in one hour, she can complete 1/5 of the job. In other words, her work ...”
August 25, 2018
Brent@GMATPrepNow posted a reply to Each of the following numbers has a remaider of 2 when in the Problem Solving forum
“A. 2 divided by 11 equals 0 with remainder 2. ELIMINATE B. 13 divided by 11 equals 1 with remainder 2. ELIMINATE C. 24 divided by 11 equals 2 with remainder 2. ELIMINATE D. 57 divided by 11 equals 5 with remainder 2. ELIMINATE By the process of elimination, the correct answer MUST be E Let''s ...”
August 25, 2018
Brent@GMATPrepNow posted a reply to If each of the two digits X and Y is distinct in the Data Sufficiency forum
“Target question: Is the two-digit integer xy prime? Given: Each of the two digits x and y is distinct Statement 1: Each of the digits x and y is the sum of 2 distinct single digit prime numbers. Let''s TEST some values. There are several values of x and y that satisfy statement 1. Here ...”
August 25, 2018
Brent@GMATPrepNow posted a reply to Is w less than y? in the Data Sufficiency forum
“Target question: Is w less than y? Statement 1: 1.3 < w < 1.3101 Since we have no information about y, there''s no way to determine whether w is less than y Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT Statement 2: 1.3033 < y Since we ...”
August 25, 2018
Brent@GMATPrepNow posted a reply to What is the sum of all of the integers in the chart above? in the Problem Solving forum
“Always check the answer choices BEFORE solving the question!! Since the answer choices are nicely spread apart, we can be quite aggressive in our estimation Let''s add the 5 numbers in each COLUMN COLUMN 1: Sum ≈500 COLUMN 2: Sum ≈-1000 COLUMN 3: Sum ≈1500 COLUMN 4: Sum ≈-2000 ...”
August 25, 2018
Brent@GMATPrepNow posted a reply to After receiving a 25% discount, Amanda pays $240 for a TV. in the Problem Solving forum
“Another approach is to TEST THE ANSWER CHOICES.... If Amanda received a 25% discount, then she paid 75% of the original price. In other words, she paid 3/4 of the original price. We''re told she paid $240, so we''ll check the answer choices to see which one yields an output of $240 when we ...”
August 25, 2018
Brent@GMATPrepNow posted a reply to After receiving a 25% discount, Amanda pays $240 for a TV. in the Problem Solving forum
“Let x = the original price (BEFORE the discount) If Amanda received a 25% discount, then she paid 75% of the original price. In other words, she paid 75% of x We''re told she paid $240, so we can write: 75% of x = $240 Or we can write: 0.75x = 240 ASIDE: One approach here is to divide ...”
August 25, 2018
Brent@GMATPrepNow posted a reply to A gambler rolls three fair six-sided dice. What is the in the Problem Solving forum
“Let''s first calculate P(same, same, different) P(same, same, different) = P(1st roll is ANY value AND 2nd roll matches 1st roll AND 3rd roll is different from first 2 rolls) = P(1st roll is ANY value) x P(2nd roll matches 1st roll) x P(3rd roll is different from first 2 rolls) = 6/6 x 1/6 x 5/6 ...”
August 25, 2018
Brent@GMATPrepNow posted a reply to Michael drives x miles due north at arrives at Point A. He in the Problem Solving forum
“At the risk of being that guy, I believe the answer is E. Here''s why: We already know that, if we start at a place on the equator and walk 40,000 km (the approximate circumference of Earth) due east, we will end up at the same place we started. If we start at a place further north (say Los ...”
August 25, 2018
Brent@GMATPrepNow posted a reply to f 412*378 = A, then which of the following is equal to 412*3 in the Problem Solving forum
“Given: (412)(378) = A We must find the value of (412)(379). (412)(379) = (412)(378 + 1) = (412)(378) + (1)(412) = A + 412 Answer: D Cheers, Brent”
August 24, 2018
Brent@GMATPrepNow posted a reply to If the sales tax on a $12.00 purchase is $0.66, what is the in the Problem Solving forum
“We can also solve this question using equivalent ratios We''re comparing sales tax to retail price We get: sales tax/retail price = $0.66/$12.00 What is the sales tax on a $20.00 purchase? Let x = the sales tax We can write: $0.66/$12.00 = x/$20.00 Cross multiply to get: (0.66)(20) = ...”
August 24, 2018
Brent@GMATPrepNow posted a reply to At a bowling alley, Neil can win a free pair of bowling in the Problem Solving forum
“At a bowling alley, Neil can win a free pair of bowling shoes if he averages a score of at least 200 over 8 games. If the average of the 8 games = 200, then we can write: (sum of all 8 scores)/8 = 200 Multiply both sides by 8 to get: sum of all 8 scores = 1600 If his scores in his first seven ...”
August 24, 2018
Brent@GMATPrepNow posted a reply to Last month, a florist gave 7 percent of her sales revenue to in the Problem Solving forum
“Choose a "nice" number for the sales revenue Let $100 = LAST MONTH''s revenue So, $120 = THIS MONTH''s revenue (since sales were up 20 percent from last month) LAST month, a florist gave 7 percent of her sales revenue to her employees in bonuses So, bonuses = 7% of $100 = $7 ...”
August 24, 2018
Brent@GMATPrepNow posted a reply to A librarian has a set of ten books, including four different in the Problem Solving forum
“Let''s first "glue" the 4 Lincoln books together to create one SUPER BOOK (this will ensure that the 4 books remain together) We now have 7 books: 6 regular books and 1 super book We can arrange these 7 books in 7! ways. KEY: For each of the 7! arrangements, we can take the 4 Lincoln ...”
August 24, 2018
Brent@GMATPrepNow posted a reply to If n is a positive integer, which of the following can’t b in the Problem Solving forum
“KEY CONCEPTS: #1) If n is an integer, then n and n+1 are consecutive integers #2)If n and n+1 are consecutive integers, then one value is ODD and the other value is EVEN #3)ODD^4 = (ODD)(ODD)(ODD)(ODD) = ODD #4)EVEN^4 = (EVEN)(EVEN)(EVEN)(EVEN) = EVEN #5)(odd)-(odd) = even #6)(odd)-(even) = ...”
August 24, 2018
Brent@GMATPrepNow posted a reply to The average (arithmetic mean) of the five numbers in a data in the Problem Solving forum
“Let a, b, c, d and e be the five numbers in the set. The average (arithmetic mean) of the five numbers in a data set is 72. So, (a + b + c + d + e)/5 = 72 Multiply both sides of the equation by 5 to get: a + b + c + d + e = 360 The average (arithmetic mean) of the first three numbers is ...”
August 24, 2018
Brent@GMATPrepNow posted a reply to What is the length of the sides of a given cube? in the Data Sufficiency forum
“IMPORTANT: For geometry Data Sufficiency questions, we are typically checking to see whether the statements "lock" a particular angle, length, or shape into having just one possible measurement. This concept is discussed in much greater detail in the following video: Target question: What ...”
August 23, 2018
Brent@GMATPrepNow posted a reply to A whole number greater than 1 has remainders of 1 when it is in the Problem Solving forum
“Let N = the number in question. If N divided by 2 leaves a remainder of 1, then N is 1 greater than some multiple of 2. This means that N - 1 must be a multiple of 2. Likewise, if N divided by 3 leaves a remainder of 1, then N is 1 greater than some multiple of 3. This means that N - 1 ...”
August 23, 2018
Brent@GMATPrepNow posted a reply to If n is the smallest integer such that 432 times n is the in the Problem Solving forum
“IMPORTANT CONCEPT: The prime factorization of a perfect square (the square of an integer) will have an even number of each prime For example: 400 is a perfect square. 400 = 2x2x2x2x5x5. Here, we have four 2''s and two 5''s This should make sense, because the even numbers allow us to split the ...”
August 23, 2018
Brent@GMATPrepNow posted a reply to United Telephone charges a base rate of $10.00 for service, in the Problem Solving forum
“Let x = the number of minutes used United Telephone charge = $10.00 + $0.25x Atlantic Call charge = $12.00 + $0.20x For what number of minutes would the bills for each telephone company be the same? In other words, for what value of x does $10.00 + $0.25x EQUAL $12.00 + $0.20x? Let''s ...”
August 23, 2018
Brent@GMATPrepNow posted a reply to Alice, Bob, Cindy, Dave and Eddie joined a three-person-a-si in the Problem Solving forum
“When the answer choices are relatively small (as they are here), we should also consider just [size=150]listing the possible outcomes[/size]. They are: ABC ABD ABE ACD ACE ADE BCD BCE BDE CDE Answer: E Cheers, Brent”
August 22, 2018
Brent@GMATPrepNow posted a reply to If x and y are integers, is x^3+3x-y an even number? in the Data Sufficiency forum
“-----ASIDE------------------------- Some important rules: 1. ODD +/- ODD = EVEN 2. ODD +/- EVEN = ODD 3. EVEN +/- EVEN = EVEN 4. (ODD)(ODD) = ODD 5. (ODD)(EVEN) = EVEN 6. (EVEN)(EVEN) = EVEN ------------------------------------- Target question: Is x³ + 3x - y an even number? ...”
August 22, 2018
Brent@GMATPrepNow posted a reply to Alice, Bob, Cindy, Dave and Eddie joined a three-person-a-si in the Problem Solving forum
“The order in which we select the 3 starters does not matter. For example, selecting Alice then Cindy and then Dave to be the starters is the SAME as selecting Cindy then Dave and then Alice to be the starters. Since order does not matter, we can use COMBINATIONS We can select 3 players from 5 ...”
August 22, 2018
Brent@GMATPrepNow posted a reply to What is the decimal equivalent of (1/5)^5? in the Problem Solving forum
“Another approach: Given: (1/5)^5 Rewrite as: 1/(5^5) Create equivalent fraction by multiplying top and bottom by 2^5 to get: 2^5/(2^5)(5^5) Simplify: 32/10^5 Simplify: 32/100,000 STOP. So, the decimal equivalent will have 32 in. Check the answer choices.....only A works. Answer: ...”
August 22, 2018
Brent@GMATPrepNow posted a reply to What is the decimal equivalent of (1/5)^5? in the Problem Solving forum
“Here''s one approach: (1/5)⁵ = (2/10)⁵ = (2⁵)/(10⁵) = 32/100,000 = 0.00032 = A Cheers, Brent”
August 21, 2018
Brent@GMATPrepNow posted a reply to In the biology lab of "Jefferson" High School ther in the Problem Solving forum
“Germs per dish = (total number of germs)/(total number of dishes) total number of germs = 0.037 x 10^5 = 3700 total number of dishes = 74000 x 10^(-3) = 74 So, Germs per dish = (3700)/(74) = (37)(100)/(37)(2) = 100/2 = 50 Answer: E Cheers, Brent”
August 21, 2018
Brent@GMATPrepNow posted a reply to One machine, working at a constant rate, can fill a certain in the Problem Solving forum
“Let''s assign a "nice" value to the entire job (a value that works well with the given information) Let''s say the machine is making widgets and an order = 8 widgets. One machine, working at a constant rate, can fill a production order in 8 hours. In other words, ONE machine can ...”
August 21, 2018
Brent@GMATPrepNow posted a reply to In the xy-coordinate plane, which of the following points in the Problem Solving forum
“APPROACH #2: Rewrite the equation in slope y-intercept form y = mx + b, where m is the slope of the line and b is the line''s y-intercept Take: kx + 3y = 6 Subtract kx from both sides: 3y = 6 - kx Divide both sides by 3 to get: y = 2 - kx/3 Rewrite as: y = (k/3)x + 2 So, the slope of the ...”
August 20, 2018
Brent@GMATPrepNow posted a reply to In the xy-coordinate plane, which of the following points in the Problem Solving forum
“APPROACH #1: The key here is "for every possible value of k" So, let''s assign a value of k and see what happens. How about k = 0? When k = 0, the equation becomes: (0)x + 3y = 6 Simplify: 3y = 6 Solve: y = 2 So, in this case, the y-coordinate must be 2! Check the answer ...”
August 20, 2018
Brent@GMATPrepNow posted a reply to The median of a data set is x and its maximum is 40. The ran in the Problem Solving forum
“Your suggestion that range = 2(maximum value - median) is not always true In fact, the only time the range = 2(maximum value - median) is when the median is the average of the minimum and maximum value. For example, in the set {1, 9, 17}, the range = 17 - 1 = 16, which is equal to 2(maximum value ...”
August 20, 2018
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Brent@GMATPrepNow posted a reply to If 75 percent of the guests at a certain banquet ordered in the Data Sufficiency forum
“Another approach for this question 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. Here, we have a population of guests, and the two characteristics are: - ordered dessert or ...”
July 19, 2018
Brent@GMATPrepNow posted a reply to The product of 4 consecutive odd integers is negative. What in the Data Sufficiency forum
“Target question: What is the largest odd integer? Given: The product of 4 consecutive odd integers is negative. It''s worth taking the time to analyze what this is telling us. If the product of 4 consecutive odd integers is negative, then there are only 2 possible scenarios: Scenario #1: ...”
July 17, 2018
Brent@GMATPrepNow posted a reply to Is x<0? in the GMAT Math forum
“Target question: Is x<0? Key Concept: ODD exponents preserve the sign of the base. In other words, POSITIVE^ODD = POSITIVE and NEGATIVE^ODD = NEGATIVE Statement 1: x^5 < 0 This is telling us that x^5 = NEGATIVE So, it must be the case that x is NEGATIVE So, the answer to the ...”
July 17, 2018
Brent@GMATPrepNow posted a reply to In the xy-plane, points A, B and C are not on the same line in the Data Sufficiency forum
“Target question: Is the slope of line BC negative? We can quickly see that statements 1 and 2 (alone) are NOT SUFFICIENT. This brings us to... Statements 1 and 2 combined If we draw the line segment AB with slope -1, then we get something like this: ...”
July 17, 2018
Brent@GMATPrepNow posted a reply to If x < 12, then it must be true that in the Problem Solving forum
“NOTE: this is one of those questions that require us to check/test each answer choice. In these situations, always check the answer choices from E to A, because the correct answer is typically closer to the bottom than to the top. For more on this strategy, see my article: ...”
July 17, 2018
Brent@GMATPrepNow posted a reply to If 8x=2^y what is the value of x, in terms of y? in the Problem Solving forum
“Another approach is to find some values of x and y that satisfy the given equation 8x = 2^y One solution that works is x = 1 and y = 3, since 8(1) = 2^3 Now take each answer choice and replace x and y with 1 and 3 respectively and see which one yields a true equation: A. 1 = 2^[3(3) - 2] ...”
July 17, 2018
Brent@GMATPrepNow posted a reply to Challenge: If line k passes through the points (48, 33) and in the Problem Solving forum
“If we sketch the two given points, we can quickly see that the slope (aka rise/run) of the line = 11/17 https://i.imgur.com/jJtP4PZ.png So, we can use this information to plot another point on the line... https://i.imgur.com/pfA3jL1.png And another point... ...”
July 11, 2018
Brent@GMATPrepNow posted a reply to Challenge question: If ABCD is a square, and XYZ in the Problem Solving forum
“If ∆XYZ is EQUILATERAL, then each angle is 60° So, if we draw a line from the center to a vertex, we''ll get two 30° angles.... https://i.imgur.com/4s2wG5R.png Now drop a line down like this to create a SPECIAL 30-60-90 right triangle https://i.imgur.com/aLVDzG4.png Since the base ...”
July 10, 2018
Brent@GMATPrepNow posted a new topic called Challenge: If line k passes through the points (48, 33) and in the Problem Solving forum
“If line k passes through the points (48, 33) and (31, 22), what is the x-intercept of line k? A) -25 10/11 B) -3 C) -1 16/17 D) 1 16/17 E) 25 10/11 Answer: B Difficulty level: 600 – 650 Source: www.gmatprepnow.com *I''ll post a solution in 2 days”
July 9, 2018
Brent@GMATPrepNow posted a reply to What is the area of the shaded region, if the area of the in the Problem Solving forum
“EXTRA PRACTICE Here are two more questions involving an equilateral triangle inscribed in a circle: - http://www.beatthegmat.com/triangle-inside-a-circle-t90961.html - http://www.beatthegmat.com/if-a-smaller-circle-is-inscribed-in-an-equilateral-triangle-t289365.html Cheers, Brent”
July 9, 2018
Brent@GMATPrepNow posted a reply to Jalal weighs twicw as much as Meena. Meena's weight is 60% in the Problem Solving forum
“An alternative approach is to assign weights that meet the given conditions. Meena''s weight is 60% of Bahar''s weight Let''s let Bahar''s weight = 100 kg So, Meena''s weight = 60 kg Jalal weighs twice as much as Meena. Since Meena weight 60 kg (see above) then Jalal''s weight = 120 kg ...”
July 8, 2018
Brent@GMATPrepNow posted a new topic called Challenge question: If ABCD is a square, and XYZ in the Problem Solving forum
“https://i.imgur.com/sd4EcIB.png If ABCD is a square, and XYZ is an equilateral triangle, then the area of the square is how many times the area of the triangle? A) (4√3)/3 B) (8√3)/3 C) 2√6 D) (16√3)/9 E) (16√2)/3 Answer: D Difficulty level: 650 – 700 Source: ...”
July 8, 2018
Brent@GMATPrepNow posted a reply to GMAT Official Guide 2019 If S = 1 + in the Problem Solving forum
“So, S = 1 + 1/4 + 1/9 + 1/16 + 1/25 + 1/36 + . . . . Now, let''s convert a few of the fractions to decimal approximations... S = 1 + 0.25 + 0.11 + 0.06 + 0.04 + . . . Add the first 4 values.... S = 1.42 + 0.04 + . . . IMPORTANT: Notice that each fraction is less than the fraction ...”
July 8, 2018
Brent@GMATPrepNow posted a reply to GMAT Official Guide 2019 In the xy-coordinate plane in the Problem Solving forum
“KEY CONCEPT: In order for a point to be ON a line, the x- and y-coordinates of the point must satisfy the equation of that line So, for example, the point (3,7) lies ON the line defined by the equation y = 2x + 1, because x = 3 and y = 7 satisfy the equation y = 2x + 1 That is, 7 = 2(3) + 1 ...”
July 7, 2018
Brent@GMATPrepNow posted a reply to GMAT Official Guide 2019 Greg assembles units of a certain in the Problem Solving forum
“GIVEN: Total pay for 2 days is $180 In order to MAXIMIZE the number of units assembled on one of the days, we must MINIMIZE the number of units assembled on the other day We''re told that Greg assembled at least 30 units each day. So, the MINIMUM is 30 units Let''s say that Greg assembled 30 ...”
July 7, 2018
Brent@GMATPrepNow posted a reply to GMAT Official Guide 2019 Which of the following is closest in the Problem Solving forum
“ALWAYS check the answer choices before solving the question! When we do so, we see that the answer choices are VERY spread apart, which means we can save a ton of time by being super aggressive with our approximations (aka rounding) So, we get: √[(4.2)(1590)/15.7 ≈ √[(4)(1600)/16] ≈ ...”
July 6, 2018
Brent@GMATPrepNow posted a reply to Challenge question: In the above figure, the small circle... in the Problem Solving forum
“If we recognize that the hypotenuse of the blue right triangle below is twice the length of one side, we can see that this is a 30-60-90 SPECIAL TRIANGLE https://i.imgur.com/qxIw8NQ.png In the base triangle (on the right), the side opposite the 30° has length 1. So, the magnification factor of ...”
July 5, 2018
Brent@GMATPrepNow posted a reply to GMAT Official Guide 2019 In the figure shown in the Problem Solving forum
“Since angles on a line must add to 180°, we can see that there are three 30° angles in our diagram... https://i.imgur.com/V6wFovz.png Next, let''s focus on the BLUE triangle. https://i.imgur.com/cdsQPY8.png Since angles in a triangle must add to 180° (and since we already have two angles ...”
July 4, 2018