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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 ## Machines X and Y work at their respective constant rates. Ho ##### This topic has 1 expert reply and 0 member replies ### Top Member ## Machines X and Y work at their respective constant rates. Ho ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Machines X and Y work at their respective constant rates. How many more hours does it take machine Y, working alone, to fill a production order of a certain size than it takes machine X, working alone? (1) Machines X and Y, working together, fill a production order of this size in two-thirds the time that machine X, working alone, does (2) Machine Y, working alone, fills a production order of this size in twice the time that machine X, working alone, does OA E Source: GMAT Prep ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15348 messages Followed by: 1864 members Upvotes: 13060 GMAT Score: 790 Top Reply BTGmoderatorDC wrote: Machines X and Y work at their respective constant rates. How many more hours does it take machine Y, working alone, to fill a production order of a certain size than it takes machine X, working alone? (1) Machines X and Y, working together, fill a production order of this size in two-thirds the time that machine X, working alone, does (2) Machine Y, working alone, fills a production order of this size in twice the time that machine X, working alone, does Statement 1: Time and rate are RECIPROCALS. Since X and Y together take 2/3 as long as X alone, X and Y together work 3/2 as fast as X alone. Thus, if X's rate alone = 2 units per hour, then X and Y's combined rate = (3/2)(2) = 3 units per hour, implying that Y's rate alone = 3-2 = 1 unit per hour. Case 1: Job = 6 widgets At a rate of 2 units per hour, the time for X alone = w/r = 6/2 = 3 hours. At a rate of 1 unit per hour, the time for Y alone = w/r = 6/1 = 6 hours. In this case, Y's time - X's time = 6-3 = 3 hours. Case 2: Job = 600 widgets At a rate of 2 units per hour, the time for X alone = w/r = 600/2 = 300 hours. At a rate of 1 unit per hour, the time for Y alone = w/r = 600/1 = 600 hours. In this case, Y's time - X's time = 600-300 = 300 hours. Since the time difference can be different values, INSUFFICIENT. Cases 1 and 2 also satisfy statement 2: In each case, Y's time is twice X's time. Thus, even when both statements are satisfied, the time difference can be different values, implying that the two statements combined are INSUFFICIENT. 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. • Free Practice Test & Review How would you score if you took the GMAT Available with Beat the GMAT members only code • Free Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code • 5-Day Free Trial 5-day free, full-access trial TTP Quant Available with Beat the GMAT members only code • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • 5 Day FREE Trial Study Smarter, Not Harder Available with Beat the GMAT members only code • Award-winning private GMAT tutoring Register now and save up to$200

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