One pump can fill a pool in 12 minutes. Working with a second slower pump, the pumps together can fill the pool in 10 minutes. How fast (in minutes) can the second pump fill the pool by itself?

Answer 1

1/12 + 1/x = 1/10

multiply both sides by 60x

5x + 60 = 6x

x = 60

2nd pump does it alone in 60 minutes = 1 hour

1/12 + 1/60 = 1/10

.08 + ,02 = .10

these are the fractions of what they do in 1 minute

1st does 1/12 of the job in in 1 minute, add 2nd does 1/60 of the job in one minute

together they do 1/10 of the job in 1 minute