Question

One hose can fill a goldfish pond in 14 minutes and two hoses can fill the same pond in 10 minutes. Find how long it takes the second hose alone to fill the pond.

Answer 1

35 minutes

Explanation:

The rate of filling from the first hose is 1/14 ponds per minute. From both hoses, the rate is 1/10 ponds per minute. Then the rate of filling from the second hose is the difference of these:

(1/10 -1/14) = (14 -10)/(10·14) = 4/140 = 1/35 . . . . ponds/minute

So, the second hose can fill the pond in 35 minutes.