GMAT Prep #2_PS Rates and Work #37

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by Bill@VeritasPrep » Sun Apr 01, 2012 7:27 pm
To minimize B's time, we must maximize A's time.

If A works the full 8 hours, it will produce 9000*8=72000 pencils. Since we need 100,000 pencils, this leaves 28,000 for B to do.

28,000/7000 = 4 hours.
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by Anurag@Gurome » Sun Apr 01, 2012 7:28 pm
kwah wrote:Attached is a question from GMAT Prep Test #2.

What is the most efficient way of achieving the result?

Answer: A

Thanks,
K
To find the least amount of time that machine B must operate, the time taken for which machine A must operate should be maximized, which is 8 hours, because it is given that each machine can operate for at most 8 hours.
Now, in 8 hours machine A can produce 8 * 9,000 = 72,000 pencils
Number of pencils left to produce = 100,000 - 72,000 = 28,000
Therefore, machine B can produce 28,000 pencils in 28,000/7,000 = 4 hours

The correct answer is A.
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