Work Problem

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Work Problem

by meovang87 » Fri Oct 26, 2012 2:39 am
There are 10 machines working in the production line (given that each machine works at constant rate), it takes 10 machines 16 hours to complete the job. How many hours will it take 8 machines to complete the job ?

Answer is : 20 hours

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by GMATGuruNY » Fri Oct 26, 2012 3:16 am
meovang87 wrote:There are 10 machines working in the production line (given that each machine works at constant rate), it takes 10 machines 16 hours to complete the job. How many hours will it take 8 machines to complete the job ?
Since the amount of work is the same regardless of the number of machines, we get the following INVERSE RELATIONSHIP:
(number of machines)(time) = (number of machines)(time)
As the number of machines DECREASES, the amount of time must INCREASE, so that the amount of work produced remains CONSTANT.

Thus:
(10 machines)(16 hours) = (8 machines)(x hours)
10*16 = 8x
x = 20.
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