how many gallons?

Question

a circular plastic wading pool contains 100 gallons of water when it is 18 inches deep. on a hot day, children splashing reduces the depth of the water to 13 inches. to the nearest gallon, how much water is in the pool when the depth is 13 inches?

Answer 1

100 : 18 :: w : 13               reduce left side

50 : 9 :: w : 13                   product means/extremes

9w = 650                           divide both sides by 9

w = 72.222...

 

The pool has 72 gallons of water.