An adjustable intake valve fills the first 12 gallons of a 24-gallon tank at a rate of 28 gallons per minute. What average rate, in gallons per minute, must the valve allow while filling the remaining 12 gallons in order to have an average rate of 40 gallons per minute for filling the whole tank?
(A) 52 gallons per minute
(B) 60 gallons per minute
(C) 65 gallons per minute
(D) 70 gallons per minute
(E) 72 gallons per minute
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
Valve Problem (Knewton Prep)
This topic has expert replies
-
RadiumBall
- Master | Next Rank: 500 Posts
- Posts: 132
- Joined: Thu Dec 02, 2010 2:49 am
- Thanked: 5 times
-
GMATGuruNY
- GMAT Instructor
- Posts: 15539
- Joined: Tue May 25, 2010 12:04 pm
- Location: New York, NY
- Thanked: 13060 times
- Followed by:1906 members
- GMAT Score:790
Time to fill whole 24 gallon tank at a rate of 40 gallons per minute:RadiumBall wrote:An adjustable intake valve fills the first 12 gallons of a 24-gallon tank at a rate of 28 gallons per minute. What average rate, in gallons per minute, must the valve allow while filling the remaining 12 gallons in order to have an average rate of 40 gallons per minute for filling the whole tank?
(A) 52 gallons per minute
(B) 60 gallons per minute
(C) 65 gallons per minute
(D) 70 gallons per minute
(E) 72 gallons per minute
t = w/r = 24/40 = 3/5 minutes.
Time to fill the first 12 gallons at a rate of 28 gallons per minute:
t = w/r = 12/28 = 3/7 minutes.
Time to fill second 12 gallons:
Time to fill whole tank - time to fill first 12 gallons = 3/5 - 3/7 = 6/35 minutes.
Rate to fill second 12 gallons:
r = w/t = 12/(6/35) = 70.
The correct answer is D.
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
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
-
RadiumBall
- Master | Next Rank: 500 Posts
- Posts: 132
- Joined: Thu Dec 02, 2010 2:49 am
- Thanked: 5 times
