BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Work Problem

Expert replies
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

Thank you all for your help :)
Join the discussion
Source: — Problem Solving |

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.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Join the discussion