SOLUTION: A 5-horsepower (hp) pump can empty a pool in 5 hours. A smaller, 2-hp pump empties the same pool in 8 hours. The pumps are used together to start emptying the pool. After three hou

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A 5-horsepower (hp) pump can empty a pool in 5 hours. A smaller, 2-hp pump empties the same pool in 8 hours. The pumps are used together to start emptying the pool. After three hou      Log On


   

Question 53079: A 5-horsepower (hp) pump can empty a pool in 5 hours. A smaller, 2-hp pump empties the same pool in 8 hours. The pumps are used together to start emptying the pool. After three hours, the 2-hp pump breaks down. How much longer will it take the larger pump to finish emptying the pool, in hours and minutes?
Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
Together:
1%2F5%2B1%2F8=13%2F40
3 HOurs:
3%2813%2F40%29 --> 39%2F40 so there is 1%2F40 left:
EQUATION:
x%2F5=1%2F40
Solve and u get x=0.125 or 0.125(60)=7.5 minutes.
Paul.