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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 ## Salad dressing A is made up of 30% vinegar and 70% oil... tagged by: swerve ##### This topic has 2 expert replies and 0 member replies ### Top Member ## Salad dressing A is made up of 30% vinegar and 70% oil... Salad dressing A is made up of 30% vinegar and 70% oil, and salad dressing B contains 10% vinegar and 90% oil. If the 2 dressing are combined to produce a salad dressing that is 15% vinegar, dressing A comprises what % of the new dressing? A. 15% B. 20% C. 25% D. 40% E. 55% The OA is C. Please, can any expert explain this PS question for me? I can't get the correct answer. I need your help. Thanks. ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15380 messages Followed by: 1872 members Upvotes: 13060 GMAT Score: 790 swerve wrote: Salad dressing A is made up of 30% vinegar and 70% oil, and salad dressing B contains 10% vinegar and 90% oil. If the 2 dressing are combined to produce a salad dressing that is 15% vinegar, dressing A comprises what % of the new dressing? A. 15% B. 20% C. 25% D. 40% E. 55% Vinegar in A = 30%. Vinegar in B = 10%. Vinegar in the MIXTURE of A and B = 15%. To determine the ratio of A to B, use ALLIGATION -- a very efficient way to handle mixture problems. Step 1: Plot the 3 percentages on a number line, with the percentages for A and B (30% and 10%) on the ends and the percentage for the mixture (15%) in the middle. A 30----------15-----------10 B Step 2: Calculate the distances between the percentages. A 30----15----15----5----10 B Step 3: Determine the ratio in the mixture. The required ratio of A to B is equal to the RECIPROCAL of the distances in red. A:B = 5:15 = 1:3. Thus, of every 4 liters: A = 1 liter. B = 3 liters. A/total = 1/4 = 25%. The correct answer is C. Other alligation problems: http://www.beatthegmat.com/mixture-problem-rabbit-proteins-t190121.html#593241 _________________ 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. ### GMAT/MBA Expert GMAT Instructor Joined 09 Apr 2015 Posted: 1465 messages Followed by: 19 members Upvotes: 39 swerve wrote: Salad dressing A is made up of 30% vinegar and 70% oil, and salad dressing B contains 10% vinegar and 90% oil. If the 2 dressing are combined to produce a salad dressing that is 15% vinegar, dressing A comprises what % of the new dressing? A. 15% B. 20% C. 25% D. 40% E. 55% We can let the amount of dressing A = a and the amount of dressing B = b, thus: 0.3a + 0.1b = 0.15(a + b) 30a + 10b = 15a + 15b 15a = 5b 3a = b So dressing A is a/(a + b) = a/(a + 3a) = 1/4 = 25% of the new dressing. Answer: C _________________ Jeffrey Miller Head of GMAT Instruction jeff@targettestprep.com See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE 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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