SOLUTION: An inlet pipe on a swimming pool can be used to fill the pool in 9 hours. The drain pipe can be used to drain the pipe in 10 hours. If the pool is 2/5 filled and then the inlet pip

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Question 766501: An inlet pipe on a swimming pool can be used to fill the pool in 9 hours. The drain pipe can be used to drain the pipe in 10 hours. If the pool is 2/5 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 ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
An inlet pipe on a swimming pool can be used to fill the pool in 9 hours.
The drain pipe can be used to drain the pipe in 10 hours.
If the pool is 2/5 filled and then the inlet pipe and drain pipe are opened,
how long from that time will it take to fill the pool?
:
Let t = time required to finish filling the pool
:
Let a full pool = 1
The pool is already 2/5 filled, therefore 3/5 remain to filled
:
t%2F9 - t%2F10 = 3%2F5
multiplied eq by 90 to clear the denominators, results:
10t - 9t = 18(3)
t = 54 hrs to fill the pool under these conditions