AAPL wrote:Five drainage pipes, each draining water from a pool at the same constant rate, together can drain a certain pool in 12 days. How many additional pipes, each draining water at the same constant rate, will be needed to drain the pool in 4 days?
A) 6
B) 9
C) 10
D) 12
E) 15
Let the rate for each pipe = 1 liter per day, implying that the rate for 5 pipes = 5 liters per day.
Since the pool is drained by 5 pipes in 12 days, the pool = rt = 5*12 = 60 liters.
To drain the 60-liter pool in 4 days, the required rate = w/t = 60/4 = 15 liters per day.
Since the rate must increase from 5 liters per day to 15 liters per day -- an increase of 10 liters per day -- 10 additional pipes are needed.
The correct answer is
C.
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
