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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 ## What is the difference between the areas of the squares ABCD tagged by: fskilnik@GMATH ##### This topic has 2 expert replies and 0 member replies ### GMAT/MBA Expert ## What is the difference between the areas of the squares ABCD ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult GMATH practice exercise (Quant Class 15) What is the difference between the areas of the squares ABCD and EFGC, in that order? (1) The area of the shaded triangle CDE is 30. (2) The ratio of the areas of the squares ABCD and EFGC, in that order, is 25/9. Answer: ____(C)__ _________________ 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 09 Oct 2010 Posted: 1449 messages Followed by: 32 members Upvotes: 59 Top Reply fskilnik@GMATH wrote: GMATH practice exercise (Quant Class 15) What is the difference between the areas of the squares ABCD and EFGC, in that order? (1) The area of the shaded triangle CDE is 30. (2) The ratio of the areas of the squares ABCD and EFGC, in that order, is 25/9. $$?\,\, = \,\,{S_{{\rm{ABCD}}}} - {S_{{\rm{EFGC}}}}$$ (Click on the image to have it "zoomed"!) $$\left. \matrix{ \left( {1 + 2} \right)\,\,\,\,? = \,{\left( {5k} \right)^2} - {\left( {3k} \right)^2} = 16{k^2} \hfill \cr 30 = {S_{\Delta {\rm{CDE}}}} = {{3k \cdot 5k} \over 2}\,\,\,\,\, \Rightarrow \,\,\,\,{k^2} = 4\,\,\, \hfill \cr} \right\}\,\,\,\,\, \Rightarrow \,\,\,\,\,? = 16 \cdot 4\,\,\,\, \Rightarrow \,\,\,\,{\rm{SUFF}}.$$ The correct answer is (C). We follow the notations and rationale taught in the GMATH method. Regards, Fabio. POST-MORTEM: this problem is presented in our Quant Class 17 (not 15)... we thank our students for the correction! _________________ 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 25 May 2010 Posted: 15387 messages Followed by: 1872 members Upvotes: 13060 GMAT Score: 790 fskilnik@GMATH wrote: [size=17]GMATH practice exercise (Quant Class 15) What is the difference between the areas of the squares ABCD and EFGC, in that order? (1) The area of the shaded triangle CDE is 30. (2) The ratio of the areas of the squares ABCD and EFGC, in that order, is 25/9 Statement 1: Case 1: DC=10 and EC=6, with the result that CDE = (1/2)(10)(6) = 30 In this case, ABCD-EFGC = 10Â² - 6Â² = 100 - 36 = 64. Case 2: DE=20 and EC=3, with the result that CDE = (1/2)(20)(3) = 30 In this case, ABCD-EFGC = 20Â² - 3Â² = 400 - 9 = 391. Since ABCD-EFGC can be different values, INSUFFICIENT. Statement 2: Case 3: ABCD=25 and EFCG=9 In this case, ABCD-EFGC = 25 - 9 = 16. Statement 2 implies the following: DCÂ²/ECÂ² = 25/9 DC/EC = 5/3. Case 1 satisfies the condition that DC/EC = 5/3. In Case 1, ABCD-EFGC = 64. Since ABCD-EFGC can be different values, INSUFFICIENT. Statements combined: Only Case 1 satisfies both statements. In Case 1, ABCD-EFGC = 64. SUFFICIENT. The correct answer is C. _________________ 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. • Free Veritas GMAT Class Experience Lesson 1 Live 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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