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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## Sets X and Y consist solely of positive integers. Each set tagged by: vinni.k ##### This topic has 1 expert reply and 2 member replies ### Top Member ## Sets X and Y consist solely of positive integers. Each set Sets X and Y consist solely of positive integers. Each set contains at least two elements, and no element appears more than once within a set. Sets X and Y contain the same number of elements. Is the standard deviation of set X greater than the standard deviation of set Y? (1) The positive difference between the range of set X and set Y is 12 (2) Each element of set Y is the square if an element of set X OA is B Please let me know if i am correct in s(1). My working for S(1):- X = {1,22,23,24,25} range of set X = 25 - 1 = 24 Y = {2,5,8,11,14} range of set Y = 14 - 2 = 12 The positive difference between the range of set X and set Y = 24 - 12 Here, SD(X) < SD(Y). So, NO X = {1,25} range of set X = 25 - 1 = 24 Y = {0,12} range of set Y = 14 - 2 = 12 The positive difference between the range of set X and set Y = 24 - 12 But here SD(X) > SD(Y) . So, YES Because after getting the average of both the sets the measure of dispersion will be {1,23,25} and {0,6,12} Please let me if i am wrong. Regards ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 14932 messages Followed by: 1855 members Upvotes: 13060 GMAT Score: 790 Top Reply vinni.k wrote: Sets X and Y consist solely of positive integers. Each set contains at least two elements, and no element appears more than once within a set. Sets X and Y contain the same number of elements. Is the standard deviation of set X greater than the standard deviation of set Y? (1) The positive difference between the range of set X and set Y is 12 (2) Each element of set Y is the square if an element of set X Statement 1: We don't know which set has the greater range. More importantly, we know nothing about the how the values in each set are dispersed from the mean. Thus, we cannot determine which set has the greater SD. INSUFFICIENT. Statement 2: X = (1, 2), Y = (1, 4) X = (1, 3, 5), Y = (1, 9, 25) X = (10, 20, 30), Y = (100, 400, 900) As the cases above illustrate, the values in X are less spread out than are the values in Y. Thus, the SD of X is less than the SD of Y. SUFFICIENT. The correct answer is B. _________________ Mitch Hunt Private Tutor for the GMAT and GRE GMATGuruNY@gmail.com If you find one of my posts helpful, please take a moment to click on the "UPVOTE" icon. Available for tutoring in NYC and long-distance. For more information, please email me at GMATGuruNY@gmail.com. Student Review #1 Student Review #2 Student Review #3 Free GMAT Practice Test How can you improve your test score if you don't know your baseline score? Take a free online practice exam. Get started on achieving your dream score today! Sign up now. ### Top Member Master | Next Rank: 500 Posts Joined 17 Apr 2011 Posted: 420 messages Followed by: 2 members Upvotes: 6 Test Date: 2016 Target GMAT Score: 700+ GMAT Score: 620 Can anyone please let me know whether my approach is correct ? or i am missing something. I always lack in coming up with different set of numbers in SD, but these days i am trying with different set of numbers, thereby I am taking time in such questions but accuracy is going up. Can you please tell me what is the correct approach or sets of numbers that i can use for this question? Thanks & Regards ### Top Member Master | Next Rank: 500 Posts Joined 17 Apr 2011 Posted: 420 messages Followed by: 2 members Upvotes: 6 Test Date: 2016 Target GMAT Score: 700+ GMAT Score: 620 GMATGuruNY wrote: Statement 1: We don't know which set has the greater range. INSUFFICIENT. Mitch, Thanks for your reply. From your explanation what i have understand is that "The positive difference between the range of set X and set Y" does not only mean X - Y = 12, but it can also mean Y - X = 12. X - Y = 12 Y - X = 12 & SD can change Suppose X = {1,22,23,24,25} range of set X = 25 - 1 = 24 Y = {2,5,8,11,14} range of set Y = 14 - 2 = 12 Here, SD(X) < SD(Y). But, if i change X = {2,5,8,11,14} range of set Y = 14 - 2 = 12 Y = {1,22,23,24,25} range of set X = 25 - 1 = 24 Here, SD(X) > SD(Y). Am i correct. • Free Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code • Free Practice Test & Review How would you score if you took the GMAT Available with Beat the GMAT members only code • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • FREE GMAT Exam Know how you'd score today for$0

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