SOLUTION: A water tank can be filled in 20 hours by an inlet pipe and emptied in 25 hours by an outlet pipe. How long will it take to fill the tank if both pipes are left open?

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Question 1032971: A water tank can be filled in 20 hours by an inlet pipe and emptied in 25 hours by an outlet pipe. How long will it take to fill the tank if both pipes are left open?
Found 2 solutions by Alan3354, ikleyn:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
A water tank can be filled in 20 hours by an inlet pipe and emptied in 25 hours by an outlet pipe. How long will it take to fill the tank if both pipes are left open?
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Each hour, 1/20 of the tank flows in and 1/25 of the tank flows out.

Answer by ikleyn(52782) About Me  (Show Source):
You can put this solution on YOUR website!
.
A water tank can be filled in 20 hours by an inlet pipe and emptied in 25 hours by an outlet pipe. How long will it take to fill the tank if both pipes are left open?
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Each hour, 1/20 of the tank flows in and 1/25 of the tank flows out.

So, the net balance is 1%2F20+-+1%2F25 = 25%2F500+-+20%2F500 = 5%2F500 = 1%2F100 of the tank volume is filling each hour.

Therefore, it will take 100 hour to fill the tank if both pipes are left open.

Answer. 100 hours.


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