Rudy414 wrote:6 machines working at a constant rate can complete a job in 12 days. How many additional machines working at the same constant rate are needed to complete the job in 8 days?
2
3
4
6
8
Thank you!
The number of machines is INVERSELY PROPORTIONAL to the number of days:
(machines)(days) = (machines)(days)
As the number of machines INCREASES, the number of days must DECREASE, so that in each case the SAME AMOUNT OF WORK is produced.
Since 6 machines take 12 days, and the job is to be completed in 8 days, we get:
6 * 12 = m * 8
72 = 8m
m = 9.
Since 9 machines are required, the original number of machines -- 6 -- must increase by 3.
The correct answer is
B.
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
