SOLUTION: Pump A can fill a swimming pool in 30 hours, while working together with pump B they will fill the pool in 12 hours. How much time would it take pump B to fill the pool?

Question 713049: Pump A can fill a swimming pool in 30 hours, while working together with pump B they will fill the pool in 12 hours. How much time would it take pump B to fill the pool?
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
One job is filling the pool. Rate as gallons per hours.
Rate*Time=Jobs

Pump__________rate__________time_____________jobs
A_____________1/30_____________30____________1
B______________r______________()____________1
A & B__________1/12______________12_____________1

While A and B work together, each pump contributes its own rate to the sum of the simultaneous rates.

, find r, which is units of jobs per hour. Note that the question is asking how many hours to fill the pool by pump B alone, which means how many hours per 1 job. This is the RECIPROCAL of r. We essentially are looking for in the above table.

,
Answer: That means 10 hours for pump B to fill the pool
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