Question

With water from one hose, a swimming pool can be filled in 9 hours. A second, larger hose used alone can fill the pool in 2 hours. How long would it take to fill the pool if both hoses were used simultaneously?

Answer 1

1/9 + 1/2 = 1/x

Let x = length of time it will take both hoses to work together

Multiply both sides by 18x.

2x + 9x = 18

10x = 18

x = 18/10

x = 9/5

x = 1.8 hours

In other words, if both hoses work together, the pool can be filled in 1 hour and 48 minutes.