swerve wrote: ↑

Mon Jul 20, 2020 11:42 am

Three machines operating independently, simultaneously, and at the same constant rate can fill a certain production order in 36 hours. If one additional machine were used under the same operating conditions, in how many fewer hours of simultaneous operation could the production order be fulfilled?

A. 6
B. 9
C. 12
D. 27
E. 48

The OA is B

Source: GMAT Prep

Given that three machines operating independently, simultaneously, and at the same constant rate can fill a certain production order in 36 hours, one machine can do the same work in 36*3 = 108 hours.

Thus, 4 similar machines would do the 108-hour work in 108/4 = 27 hours.

Saving in time = 36 – 27 = 9 hours

Correct answer: B

Hope this helps!

-Jay
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