A pool can be filled with water in 16 minutes. It has developed a hole through which the pool will drain from in 20 minutes. How long will it take to fill the pool if the hole is not repaired?

Question

Word Problems

Answer 1

If the volume of the pool is V gallons then the filling rate is V/16 gals/min, the emptying rate is V/20.

The difference between these tells us the rate of filling when there is a hole:

V/16-V/20=V/80 gals/min. So it will take V/(V/80)=80 mins to fill (but it will continue to empty).