Hi All,

This question can be solved in a couple of different ways (depending on how quickly you 'see' the pattern involved). You can also TEST VALUES to define the pattern.

We're told that a swimming pool doubles its volume of water every hour...

IF... you start at the beginning....

Start = 1 gallon

Hour 1 = 2 gallons

Hour 2 = 4 gallons

Hour 3 = 8 gallons

Hour 4 = 16 gallons

Hour 5 = 32 gallons

Hour 6 = 64 gallons

Hour 7 = 128 gallons

Hour 8 = 256 gallons = FULL

The question asks at what point the pool was 1/4 full. Since 1/4 of 256 = 64, we know exactly when it was 1/4 full.

IF... you start from the end....

Hour 8 = FULL

Hour 7 = 1/2 full

Hour 6 = (1/2)(1/2) = 1/4 full

Either way, you have the correct answer.

Final Answer:

GMAT assassins aren't born, they're made,

Rich

_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels

Contact Rich at: Rich.C@empowergmat.com

# Rich Cohen

Co-Founder & GMAT Assassin

Special Offer:

Save $75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee

www.empowergmat.com/
*****Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*****