SOLUTION: 2 pipes are connected to a tank. One pipe fills the tank in 7 hours. The second pipe empties the tank in 9 hours. If both pipes are open, how long will it take to fill the tank?
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-> SOLUTION: 2 pipes are connected to a tank. One pipe fills the tank in 7 hours. The second pipe empties the tank in 9 hours. If both pipes are open, how long will it take to fill the tank?
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Question 380401: 2 pipes are connected to a tank. One pipe fills the tank in 7 hours. The second pipe empties the tank in 9 hours. If both pipes are open, how long will it take to fill the tank? Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website! In each hour, the filler pipe adds 1/7 of the tank while the drain subtracts 1/9 of the tank.
--> 1/7 - 1/9 per hour
= 2/63 tank per hour
--> 63/2 hours per tank = 31.5 hours
