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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 ## Which data set has the greater standard deviation, data set ##### This topic has 3 expert replies and 0 member replies ### Top Member ## Which data set has the greater standard deviation, data set ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Which data set has the greater standard deviation, data set K or data set L? (1) Every element in data set K is a multiple of 3. (2) Every element in data set L is a multiple of 9. OA E Source: Magoosh ### GMAT/MBA Expert GMAT Instructor Joined 25 Apr 2015 Posted: 2424 messages Followed by: 18 members Upvotes: 43 Top Reply BTGmoderatorDC wrote: Which data set has the greater standard deviation, data set K or data set L? (1) Every element in data set K is a multiple of 3. (2) Every element in data set L is a multiple of 9. Every element in data set K is a multiple of 3. Since we donâ€™t know anything about set L, statement one alone is not sufficient. Statement Two Alone: Every element in data set L is a multiple of 9. Since we donâ€™t know anything about set K, statement two alone is not sufficient. Statements One and Two Together: Even with both statements, itâ€™s still not sufficient to answer the question. For example, if set K is {3, 6} and set L is {9, 18}, then set L has a larger standard deviation (recall that numbers are further apart from one another produce a larger standard deviation). However, if set K is {3, 3} and set L is {9, 9}, then the standard deviation of set K and set L is equal, and itâ€™s 0 (recall that a set with all numbers the same has standard deviation of 0). Answer: E _________________ Scott Woodbury-Stewart Founder and CEO scott@targettestprep.com See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews ### GMAT/MBA Expert GMAT Instructor Joined 09 Oct 2010 Posted: 1449 messages Followed by: 32 members Upvotes: 59 Top Reply BTGmoderatorDC wrote: Which data set has the greater standard deviation, data set K or data set L? (1) Every element in data set K is a multiple of 3. (2) Every element in data set L is a multiple of 9. Source: Magoosh $?\,\,:\,\,\,{\sigma _{\max }}\,\,\left( {K\,\,{\text{or}}\,\,L} \right)$ $\left( {1 + 2} \right)\,\,\,\left\{ \begin{gathered} \,{\text{Take}}\,\,{\text{K}} = \left\{ {0,0} \right\}\,\,\,;\,\,\,L = \left\{ {0,9} \right\}\,\,\,\, \Rightarrow \,\,\,\,? = L \hfill \\ \,{\text{Take}}\,\,{\text{K}} = \left\{ {0,3} \right\}\,\,\,;\,\,\,L = \left\{ {0,0} \right\}\,\,\,\, \Rightarrow \,\,\,\,? = K \hfill \\ \end{gathered} \right.$ The correct answer is therefore (E). This solution follows the notations and rationale taught in the GMATH method. Regards, Fabio. POST-MORTEM: in this very special situation, a careful reader may correctly mention that K=L={0} is enough to guarantee the correct answer is (E). (We donÂ´t want to explain this delicate issue here. We have just mentioned it because our own students will correctly think about that option at once!) _________________ Fabio Skilnik :: GMATH method creator ( Math for the GMAT) English-speakers :: https://www.gmath.net Portuguese-speakers :: https://www.gmath.com.br ### GMAT/MBA Expert GMAT Instructor Joined 22 Aug 2016 Posted: 1890 messages Followed by: 30 members Upvotes: 470 BTGmoderatorDC wrote: Which data set has the greater standard deviation, dataset K or dataset L? (1) Every element in dataset K is a multiple of 3. (2) Every element in dataset L is a multiple of 9. OA E Source: Magoosh Certainly, each statement is not sufficient since each statement gives information about only one dataset. Combining the two statements, we get Case 1: Say dataset K: {3, 3} and dataset L: {9, 18} Standard deviation of dataset K = 0 since each element is the same; however, standard deviation of dataset L > 0 since each element is NOT same. The answer is dataset L. Case 2: Say dataset K: {3, 6} and dataset L: {9, 9} Standard deviation of dataset L = 0 since each element is the same; however, standard deviation of dataset K > 0 since each element is NOT same. The answer is dataset K. No unique answer. Insufficient. The correct answer: E Hope this helps! -Jay _________________ Manhattan Review GMAT Prep Locations: Manhattan Review India | Manhattan Review Hyderabad | Dilsukhnagar GMAT Courses | Mehdipatnam GRE Prep | and many more... Schedule your free consultation with an experienced GMAT Prep Advisor! Click here. • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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