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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 tank has 5 inlet pipes. Three pipes are narrow and two are tagged by: swerve ##### This topic has 4 expert replies and 0 member replies ### Top Member ## A tank has 5 inlet pipes. Three pipes are narrow and two are ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult A tank has 5 inlet pipes. Three pipes are narrow and two are wide. Each of the three narrow pipes works at 1/2 the rate of each of the wide pipes. All the pipes working together will take what fraction of time taken by the two wide pipes working together to fill the tank? A. 1/2 B. 2/3 C. 3/4 D. 3/7 E. 4/7 The OA is E. Source: Veritas Prep ### GMAT/MBA Expert GMAT Instructor Joined 22 Aug 2016 Posted: 1975 messages Followed by: 30 members Upvotes: 470 swerve wrote: A tank has 5 inlet pipes. Three pipes are narrow and two are wide. Each of the three narrow pipes works at 1/2 the rate of each of the wide pipes. All the pipes working together will take what fraction of time taken by the two wide pipes working together to fill the tank? A. 1/2 B. 2/3 C. 3/4 D. 3/7 E. 4/7 The OA is E. Source: Veritas Prep Say the rate of each of the two wide pipes = 1 unit Thus, the rate of each of the three narrow pipes = 1 * 1/2 = 1/2 unit Combined rate of the three narrow pipes = 3 * 1/2 = 3/2 Combined rate of the two wide pipes = 2 * 1 = 2 Combined rate of all the five pipes = 3/2 + 2 = 7/2 Thus, the fraction of time taken by the two wide pipes working together to fill the tank = 2 / (7/2) = 4/7 The correct answer: E 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: 1449 messages Followed by: 32 members Upvotes: 59 swerve wrote: A tank has 5 inlet pipes. Three pipes are narrow and two are wide. Each of the three narrow pipes works at 1/2 the rate of each of the wide pipes. All the pipes working together will take what fraction of time taken by the two wide pipes working together to fill the tank? A. 1/2 B. 2/3 C. 3/4 D. 3/7 E. 4/7 Source: Veritas Prep $5\,\,{\text{pipes}}\,\,\,\left\{ \begin{gathered} \,3\,\,{\text{narrow}}\,\,\,\, \to \,\,\,{\text{each}}\,\,\,1\,\,{\text{gallons}}/\min \,\,\, \hfill \\ \,2\,\,{\text{wide}}\,\,\,\,\,\,\,\,\, \to \,\,\,{\text{each}}\,\,\,2\,\,{\text{gallons}}/\min \hfill \\ \end{gathered} \right.\,\,\,\,\,\left( {{\text{particular}}\,\,{\text{case}}!} \right)$ ${\text{A}}\,\,\,{\text{ = }}\,\,\,{\text{2}}\,\,{\text{wide}}\,\,{\text{together}}\,\,\,{\text{:}}\,\,\,\,2 \cdot 2 = 4\,\,{\text{gallons/min}}$ ${\text{B}}\,\,\,{\text{ = }}\,\,\,{\text{all}}\,\,{\text{5}}\,\,{\text{together}}\,\,\,{\text{:}}\,\,\,\,3 \cdot 1 + 2 \cdot 2 = 7\,\,{\text{gallons/min}}$ ${\text{B:A}}\,\,\underline {{\text{work}}} \,\,{\text{ratio}}\,\,\left( {{\text{per}}\,\,{\text{any}}\,\,{\text{time}}} \right)\,\,\,{\text{ = }}\,\,\,\,\frac{7}{4}\,\,\,\,\,$ $?\,\,\, = \,\,\,B:A\,\,\underline {{\text{time}}} \,\,{\text{ratio}}\,\,\,\left( {{\text{per}}\,\,{\text{any}}\,\,{\text{work}}} \right)\,\,\, = \,\,\,{\left( {\frac{7}{4}} \right)^{ - 1}} = \,\,\,\frac{4}{7}$ 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 ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15342 messages Followed by: 1864 members Upvotes: 13060 GMAT Score: 790 swerve wrote: A tank has 5 inlet pipes. Three pipes are narrow and two are wide. Each of the three narrow pipes works at 1/2 the rate of each of the wide pipes. All the pipes working together will take what fraction of time taken by the two wide pipes working together to fill the tank? A. 1/2 B. 2/3 C. 3/4 D. 3/7 E. 4/7 Let the rate of each wide pipe = 2 liters per hour. Combined rate for 2 wide pipes = 2*2 = 4 liters per hour. Since each narrow pipe works at 1/2 the rate of each wide pipe, the rate of each narrow pipe = (1/2)(2) = 1 liter per hour. Combined rate for 3 narrow pipes and 2 wide pipes = (3*1) + (2*2) = 7 liters per hour. Let the tank 28 liters. Since the rate for all 5 pipes = 7 liters per hour, the time for all 5 pipes to fill the 28-liter tank = 28/7 = 4 hours. Since the rate for 2 wide pipes = 4 liters per hour, the time for 2 wide pipes to fill the 28-liter tank = 28/4 = 7 hours. (time for all 5 pipes)/(time for 2 wide pipes) = 4/7. The correct answer is E. _________________ 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 25 Apr 2015 Posted: 2791 messages Followed by: 18 members Upvotes: 43 swerve wrote: A tank has 5 inlet pipes. Three pipes are narrow and two are wide. Each of the three narrow pipes works at 1/2 the rate of each of the wide pipes. All the pipes working together will take what fraction of time taken by the two wide pipes working together to fill the tank? A. 1/2 B. 2/3 C. 3/4 D. 3/7 E. 4/7 We can let x = the rate of each small inlet pipe and thus 2x = the rate of each large inlet pipe. Letâ€™s now assume that it will take 10 hours to fill the pool if all the pipes work together. Thus, the capacity of the pool is 10(3x + 2(2x)) = 10(7x) = 70x. If the pool is filled only by the 2 large pipes, then it would take 70x/(2(2x)) = 70x/(4x) = 35/2 = 17.5 hours. Therefore, the ratio of the time if all 5 pipes work together to the time if only the 2 large pipes work together is 10/17.5 = 20/35 = 4/7. 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 • FREE GMAT Exam Know how you'd score today for$0

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