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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 ## A laboratory is testing a new steroid on mice. The average tagged by: BTGmoderatorLU ##### This topic has 2 expert replies and 1 member reply ### Top Member ## A laboratory is testing a new steroid on mice. The average ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Source: Veritas Prep A laboratory is testing a new steroid on mice. The average weight of a mouse that has been treated with the steroid is 26.8 grams and the average weight of a mouse that has not been treated with the steroid is 19.2 grams. If the average weight of all mice at the laboratory is 22.4 grams, what is the ratio of mice that have been treated to mice that have not been treated? A. 8:13 B. 3:4 C. 8:11 D. 8:9 E. 7:9 The OA is C. ### GMAT/MBA Expert GMAT Instructor Joined 22 Aug 2016 Posted: 1770 messages Followed by: 28 members Upvotes: 470 BTGmoderatorLU wrote: Source: Veritas Prep A laboratory is testing a new steroid on mice. The average weight of a mouse that has been treated with the steroid is 26.8 grams and the average weight of a mouse that has not been treated with the steroid is 19.2 grams. If the average weight of all mice at the laboratory is 22.4 grams, what is the ratio of mice that have been treated to mice that have not been treated? A. 8:13 B. 3:4 C. 8:11 D. 8:9 E. 7:9 The OA is C. Say, the average weight of a mouse that has been treated with the steroid = x = 26.4; the average weight of a mouse that has NOT been treated with the steroid = y = 19.2; and the average weight of all the mice = z = 22.4 Then, The ratio of mice that have been treated to mice that have not been treated = (z - y) / (x - z) = (22.4 - 19.2) / (26.8 - 22.4) = 8/11 The correct answer: C Hope this helps! -Jay _________________ Manhattan Review GRE Prep Locations: GRE Classes Los Angeles | GMAT Prep Course Singapore | GRE Prep Orlando | SAT Prep Courses Toronto | and many more... Schedule your free consultation with an experienced GMAT Prep Advisor! Click here. ### GMAT/MBA Expert GMAT Instructor Joined 09 Oct 2010 Posted: 1296 messages Followed by: 29 members Upvotes: 59 BTGmoderatorLU wrote: Source: Veritas Prep A laboratory is testing a new steroid on mice. The average weight of a mouse that has been treated with the steroid is 26.8 grams and the average weight of a mouse that has not been treated with the steroid is 19.2 grams. If the average weight of all mice at the laboratory is 22.4 grams, what is the ratio of mice that have been treated to mice that have not been treated? A. 8:13 B. 3:4 C. 8:11 D. 8:9 E. 7:9 Perfect opportunity for the alligation, a nice technique included in our course! $? = T:N\,\,\,\,\left( {{\text{see}}\,\,{\text{image}}\,\,{\text{attached}}} \right)$ $\frac{T}{{total}} = \frac{{22.4 - 19.2}}{{26.8 - 19.2}} = \frac{{3.2 \cdot \boxed{10}}}{{7.6 \cdot \boxed{10}}} = \frac{8}{{19}}$ We are done, but if you have not got the answer yet, have a look at the k technique... $?\,\,\,:\,\,\,\left\{ \begin{gathered} T = 8k \hfill \\ {\text{total}} = 19k \hfill \\ \end{gathered} \right.\,\,\,\,\,\left( {k > 0} \right)\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,N = 11k\,\,\,\,\, \Rightarrow \,\,\,\,\,?\,\,\, = \,\,\,8:11\,\,\,\,\,$ This solution follows the notations and rationale taught in the GMATH method. Regards, Fabio. _________________ Fabio Skilnik :: GMATH method creator ( Math for the GMAT) English-speakers :: https://www.gmath.net Portuguese-speakers :: https://www.gmath.com.br ### Top Member Legendary Member Joined 29 Oct 2017 Posted: 783 messages Followed by: 4 members Let the number of mice treated with steroid = x Let the number of mice NOT treated with steroid = y As per questions, we are given 28.6x + 19.2y = 22.4(x+y) or x/y = 8/11. I hope this help! Regards! • Free Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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