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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 machine at the golf ball ##### This topic has 3 expert replies and 0 member replies ### Top Member ## A machine at the golf ball A machine at the golf ball factory can produce 16 golf balls in 5 minutes. If several of these machines work independently and each machine performs at the same rate, how many machines are needed to produce 32 golf balls per minute? A) 3 B) 6 C) 8 D) 10 E) 13 How will i start the solution to this? OA D ### GMAT/MBA Expert GMAT Instructor Joined 12 Sep 2012 Posted: 2636 messages Followed by: 114 members Upvotes: 625 Target GMAT Score: V51 GMAT Score: 780 Top Reply I'd fall back on the trusty equation Work = Rate * Time. Here, we know that each machine follows the equation Work = Rate * Time 16 = Rate * 5 (since work = 16 golf balls and time = 5 minutes) Dividing both sides by 5, we get Rate = 16/5, so each machine works at a rate of 16/5 of a golf ball per minute. From here, our equation becomes 32 = (# of machines) * 16/5 * 1 (since work = 32 golf balls, each machine's rate = 16/5, and the time = 1 minute) That's a cinch to solve, and we're done! The # of machines = 10. Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now! ### GMAT/MBA Expert GMAT Instructor Joined 04 Oct 2017 Posted: 551 messages Followed by: 11 members Upvotes: 180 Top Reply Quote: A machine at the golf ball factory can produce 16 golf balls in 5 minutes. If several of these machines work independently and each machine performs at the same rate, how many machines are needed to produce 32 golf balls per minute? A) 3 B) 6 C) 8 D) 10 E) 13 Hi lheiannie07, Let's take a look at your question. The machine produces 16 golf balls in 5 minutes. 1 golf ball can be produced in (5/16) minutes. 32 golf balls can be produced in: $$=\ \frac{5}{16}\times32$$ $$=\ 5\times2\ =\ 10\$$ Therefore, one machine will produce 32 golf balls in 10 minutes. But the question asks that if several of these machines work independently and each machine performs at the same rate, how many machines are needed to produce 32 golf balls per minute? So if one machine is producing 32 golf balls in 10 minutes. Then 10 machines will be needed to produce 32 golf balls per minute. Therefore, Option D is correct. Hope it makes sense. I am available if you'd like any follow up. _________________ GMAT Prep From The Economist We offer 70+ point score improvement money back guarantee. Our average student improves 98 points. Free 7-Day Test Prep with Economist GMAT Tutor - Receive free access to the top-rated GMAT prep course including a 1-on-1 strategy session, 2 full-length tests, and 5 ask-a-tutor messages. Get started now. ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 14806 messages Followed by: 1850 members Upvotes: 13060 GMAT Score: 790 lheiannie07 wrote: A machine at the golf ball factory can produce 16 golf balls in 5 minutes. If several of these machines work independently and each machine performs at the same rate, how many machines are needed to produce 32 golf balls per minute? A) 3 B) 6 C) 8 D) 10 E) 13 Use the following equation: (machines)(time) / output = (machines)(time) / output In the equation above: Machines and time are INVERSELY PROPORTIONAL. As the number of machines increases, the amount of time required to produce the same output decreases. Machines and output are DIRECTLY PROPORTIONAL. As the number of machines increases, the amount of output also increases. Time and output are also DIRECTLY PROPORTIONAL. As the amount of time increases, the amount of output also increases. In the problem above: 1 machine takes 5 minutes to produce 16 golf balls, and we are asked how many machines are needed to produce in 1 minute 32 golf balls. Thus, we get the following equation: (1 machine)(5 minutes)/(16 golf balls) = (x machines)(1 minute)/(32 golf balls) 5/16 = x/32 x = (5)(32/16) = 5*2 = 10. The correct answer is D. _________________ 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. 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