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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 ## Machine M and Machine N working alone at their constant rate tagged by: swerve ##### This topic has 2 expert replies and 0 member replies ### Top Member ## Machine M and Machine N working alone at their constant rate ## Timer 00:00 ## Your Answer A B C D E ## Global Stats Difficult Machine M and Machine N working alone at their constant rates, non-stop, produced 6000 and 8000 nails respectively. Did machine M work longer than machine N? 1) Machine N produces 2000 more nails than machine M in one hour when each machine work at its constant rate. 2) Machine N produces twice as much as machine M in one hour when each machine work at its constant rate. The OA is B Source: GMAT Prep ### GMAT/MBA Expert GMAT Instructor Joined 22 Aug 2016 Posted: 1975 messages Followed by: 30 members Upvotes: 470 swerve wrote: Machine M and Machine N working alone at their constant rates, non-stop, produced 6000 and 8000 nails respectively. Did machine M work longer than machine N? 1) Machine N produces 2000 more nails than machine M in one hour when each machine work at its constant rate. 2) Machine N produces twice as much as machine M in one hour when each machine work at its constant rate. The OA is B Source: GMAT Prep Say Machine M works for x hours and Machine N works for y hours. We have to determine whether x > y. Let's take each statement one by one. 1) Machine N produces 2000 more nails than machine M in one hour when each machine work at its constant rate. => 2000 = 8000/y - 6000/x 1 = 4/y - 3/x => 4/y > 3/x x/y > 3/4 Case 1: Say x/y = 4/5 > 3/4, then we have y > x. Case 2: Say x/y = 5/4 > 3/4, then we have x > y. No unique answer. Insufficient. 2) Machine N produces twice as much as machine M in one hour when each machine work at its constant rate. => 8000/y = 2*(6000/x) x/y = 3/2 => x > y. Sufficient. The correct answer: B Hope this helps! -Jay _________________ Manhattan Review Locations: Manhattan Review New Delhi | GMAT Prep Malleswaram | GRE Prep Vijayawada | Mumbai GRE Coaching | and many more... Schedule your free consultation with an experienced GMAT Prep Advisor! Click here. ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15348 messages Followed by: 1864 members Upvotes: 13060 GMAT Score: 790 swerve wrote: Machine M and Machine N working alone at their constant rates, non-stop, produced 6000 and 8000 nails respectively. Did machine M work longer than machine N? 1) Machine N produces 2000 more nails than machine M in one hour when each machine work at its constant rate. 2) Machine N produces twice as much as machine M in one hour when each machine work at its constant rate. Statement 1: Case 1: N = 4000 nails per hour, M = 2000 nails per hour Since N's rate = 4000 nails per hour, the time for N to produce 8000 nails = 8000/4000 = 2 hours. Since M's rate = 2000 nails per hour, the time for M to produce 6000 nails = 6000/2000 = 3 hours. In this case, M works longer than N, so the answer to the question stem is YES. Case 2: N = 12000 nails per hour, M = 10000 nails per hour Since N's rate = 12000 nails per hour, the time for N to produce 8000 nails = 8000/12000 = 2/3 hour = 40 minutes. Since M's rate = 10000 nails per hour, the time for M to produce 6000 nails = 6000/10000 = 3/5 hour = 36 minutes In this case, N works longer than M, so the answer to the question stem is NO. Since the answer is YES in Case 1 but NO in Case 2, INSUFFICIENT. Statement 2: In other words, N is twice as fast as M. If N and M were to work for the same amount of time, then N's 8000-nail production would imply a 4000-nail production for M. Since M actually produces 6000 nails -- more than 4000 -- M must work for LONGER than N. Thus, the answer to the question stem is YES. SUFFICIENT. 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! 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