2 pumps working together empty a pool in 5 hours. The older pump can empty the pool on its own in 15 hours. How long would it take the new pump to do the job?

Question

Algebra word problems 

 

Answer 1

Let x = number of hours it takes older pump

Let y = number of hours it takes newer pump

 

Pump x + pump y take 5 hours

5(1/x + 1/y) = 1

 

x = 15

 

5(1/15 + 1/y) = 1

 

1/15 + 1/y = 1/5

1/y = 1/5 - 1/15

1/y = 3/15 - 1/15

1/y = 2/15

cross multiply

2y = 15

y = 7.5 hours