SOLUTION: Pipe A can fill a pool in 5 hours. Pipe B can fill it in 2 hours less than it takes Pipe C, a drain pipe, to empty the pool. With all 3 pipes open it takes 3 hours to fill the po

Question 498554: Pipe A can fill a pool in 5 hours. Pipe B can fill it in 2 hours less than it takes Pipe C, a drain pipe, to empty the pool. With all 3 pipes open it takes 3 hours to fill the pool. How long would it take Pipe C to empty it?
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
This is a problem of rates
Let = pipe C's rate of emptying the pool
Pipe A's rate of filling:
( 1 pool in 5 hrs )
Pipe B's rate of filling:

Pipe C's rate of emptying pool:

----------
With all 3 pipes open:

Multiply both sides by

Completing the square:

Take the square root of both sides

and, also

( can't use the negative square root )
It will take pipe C alone 5 hours to empty pool
check answer:

OK

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