SOLUTION: An inlet pipe on a swimming pool can be used to fill the pool in 21 hours. The drain pipe can be used to empty the pool in 28 hours. If the pool is 1/2 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 21 hours. The drain pipe can be used to empty the pool in 28 hours. If the pool is 1/2 filled and then the inlet pi
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Question 1054744: An inlet pipe on a swimming pool can be used to fill the pool in 21 hours. The drain pipe can be used to empty the pool in 28 hours. If the pool is 1/2 filled and then the inlet pipe and drain pipe are opened, how long from that time will it take to fill the pool?
You can put this solution on YOUR website! An inlet pipe on a swimming pool can be used to fill the pool in 21 hours. The drain pipe can be used to empty the pool in 28 hours. If the pool is 1/2 filled and then the inlet pipe and drain pipe are opened, how long from that time will it take to fill the pool?
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The inlet fills 1/21 pool per hour.
The drain fills -1/28 per hour.
Together --> 1/21 - 1/28 pools per hour.
= 1/84 pools per hour.
--> 84 hours to fill it from empty.
Starting at 1/2 full --> 42 hours.
