SOLUTION: An inlet pipe on a swimming pool can be used to fill the pool in 20 hours. The drain pipe can be used to empty the pool in 21 hours. If the pool is 1/3 filled and then the inlet pi
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-> SOLUTION: An inlet pipe on a swimming pool can be used to fill the pool in 20 hours. The drain pipe can be used to empty the pool in 21 hours. If the pool is 1/3 filled and then the inlet pi
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Question 1000750: An inlet pipe on a swimming pool can be used to fill the pool in 20 hours. The drain pipe can be used to empty the pool in 21 hours. If the pool is 1/3 filled and then the inlet pipe and drain pipe are opened, how long from that time will it take to fill the pool? Answer by addingup(3677) (Show Source):
You can put this solution on YOUR website! In 1 hour the pool fills 1/20
In 1 hour the pool empties 1/21
1/20-1/21= 1/3T Multiply all sides by 420 (20*21, it's the common denominator)
21-20= 140/T
1= 140/T Invert both terms:
1/1= T/140 Multiply both sides times 140:
140= T You need 140 hours
