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A pump started filling an empty pool with water and

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by swerve » Sat Aug 17, 2019 2:31 pm

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A pump started filling an empty pool with water and continued at a constant rate until the pool was full. At noon the pool was \(1/3\) full, and \(1\frac{1}{4}\) hours later it was \(3/4\) full. What was the total number of hours that it took the pump to fill the pool?

A. \(2\frac{1}{3}\)
B. \(2\frac{2}{3}\)
C. 3
D. \(3\frac{1}{2}\)
E. \(3\frac{2}{3}\)

The OA is C

Source: GMAT Prep
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Source: — Problem Solving |

by Ian Stewart » Sun Aug 18, 2019 5:45 am
If in 5/4 hours the pool goes from 1/3 to 3/4 full, then in 5/4 hours, 3/4 - 1/3 = 9/12 - 4/12 = 5/12 of the pool gets filled. If it takes 5/4 hours to fill 5/12 of the pool, it takes 1/4 hour to fill 1/12 of the pool, and 12/4 hours to fill 1 pool, so the answer is 12/4 = 3 hours.
For online GMAT math tutoring, or to buy my higher-level Quant books and problem sets, contact me at ianstewartgmat at gmail.com

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by Scott@TargetTestPrep » Fri Aug 23, 2019 10:36 am
swerve wrote:A pump started filling an empty pool with water and continued at a constant rate until the pool was full. At noon the pool was \(1/3\) full, and \(1\frac{1}{4}\) hours later it was \(3/4\) full. What was the total number of hours that it took the pump to fill the pool?

A. \(2\frac{1}{3}\)
B. \(2\frac{2}{3}\)
C. 3
D. \(3\frac{1}{2}\)
E. \(3\frac{2}{3}\)

The OA is C

Source: GMAT Prep
Since it took 1¼ = 5/4 hours to fill 3/4 - 1/3 = 9/12 - 4/12 = 5/12 of the pool, we can let x = the number of hours to fill the pool and create a proportion to determine how long it will take to fill the entire pool.

(5/4)/(5/12) = x/1

5/4 = 5x/12

60 = 20x

x = 3

Answer: C

Scott Woodbury-Stewart
Founder and CEO
[email protected]

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by Brent@GMATPrepNow » Fri Aug 23, 2019 10:57 am
Brent Hanneson - Creator of GMATPrepNow.com
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