SOLUTION: if it take 4 hours to fill a pool with the drain closed and 5 hours to empty a pool with the drain open, how long does it take to fill a pool with the drain open

Question 453460: if it take 4 hours to fill a pool with the drain closed and 5 hours to empty a pool with the drain open, how long does it take to fill a pool with the drain open
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
if it take 4 hours to fill a pool with the drain closed and 5 hours to empty a pool with the drain open, how long does it take to fill a pool with the drain open.
.
Let x = time (hours) it takes to fill pool w/drain open
then
x(1/4 - 1/5) = 1
multiplying both sides by 20:
x(5 - 4) = 20
x(1) = 20
x = 20 hours

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