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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 ## Jason can stack two shelves in 3 hours and Maria can stack tagged by: AAPL ##### This topic has 3 expert replies and 0 member replies ### Top Member ## Jason can stack two shelves in 3 hours and Maria can stack ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Magoosh Jason can stack two shelves in 3 hours and Maria can stack three shelves in 2 hours. How long will it take them together, working at a constant rate, to stack thirteen shelves? A. 5 hours B. 6 hours C. 6.5 hours D. 11 hours E. 12 hours OA B. ### GMAT/MBA Expert Elite Legendary Member Joined 23 Jun 2013 Posted: 10071 messages Followed by: 494 members Upvotes: 2867 GMAT Score: 800 Hi All, We're told that Jason can stack 2 shelves in 3 hours and Maria can stack 3 shelves in 2 hours. We're asked how long will it take them together, working at their constant rates, to stack thirteen shelves. This question is a 'rate' question, so you can work through the math in a number of different ways. Here's an approach that puts both rates in terms of 'output per hour': Jason stacks 2 shelves every 3 hours, so he stacks 2/3 of a shelf per hour. Maria stacks 3 shelves every 2 hours, so he stacks 3/2 of a shelf per hour. Combined, they stack 2/3 + 3/2 = 4/6 + 9/6 = 13/6 shelves per hour. We're asked how long it would take for the two to stock 13 shelves.... (X)(13/6 shelves/hour) = 13 shelves X = 13(6/13) = 6 hours Final Answer: B GMAT assassins aren't born, they're made, Rich _________________ Contact Rich at Rich.C@empowergmat.com ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15101 messages Followed by: 1859 members Upvotes: 13060 GMAT Score: 790 AAPL wrote: Magoosh Jason can stack two shelves in 3 hours and Maria can stack three shelves in 2 hours. How long will it take them together, working at a constant rate, to stack thirteen shelves? A. 5 hours B. 6 hours C. 6.5 hours D. 11 hours E. 12 hours Let each shelf = 6 pounds. Since Jason takes 3 hours to stack 2 6-pound shelves -- for a total of 12 pounds -- Jason's rate = 12/3 = 4 pounds per hour. Since Maria takes 2 hours to stack 3 6-pound shelves -- for a total of 18 pounds -- Maria's rate = 18/2 = 9 pounds per hour. Total weight of 13 6-pound shelves = 13*6 = 78 pounds. Combined rate for Jason and Maria = 4+9 = 13 pounds per hour. Time for Jason and Maria to stack the 13 shelves = 78/13 = 6 hours. The correct answer is B. _________________ 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: 1461 messages Followed by: 17 members Upvotes: 39 AAPL wrote: Magoosh Jason can stack two shelves in 3 hours and Maria can stack three shelves in 2 hours. How long will it take them together, working at a constant rate, to stack thirteen shelves? A. 5 hours B. 6 hours C. 6.5 hours D. 11 hours E. 12 hours The combined rate of Jason and Maria is 2/3 + 3/2 = 4/6 + 9/6 = 13/6. So it takes them 13/(13/6) = 13 x 6/13 = 6 hours to stack 13 shelves. Answer: B _________________ Jeffrey Miller Head of GMAT Instruction • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • 5 Day FREE Trial Study Smarter, Not Harder Available with Beat the GMAT members only code • FREE GMAT Exam Know how you'd score today for$0

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