SOLUTION: A water tank is connected to the two pumps. It takes 40 minutes to fill the tank from the pump at the top and 60 minutes to empty using the the pump at the bottom.. If we pump the

Question 399891: A water tank is connected to the two pumps. It takes 40 minutes to fill the tank from the pump at the top and 60 minutes to empty using the the pump at the bottom.. If we pump the water at the same time, how many hours will it take to fill the tank from empty?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
A water tank is connected to the two pumps. It takes 40 minutes to fill the tank from the pump at the top and 60 minutes to empty using the the pump at the bottom.. If we pump the water at the same time, how many hours will it take to fill the tank from empty?
...
pump A ----- 40 minutes filling
so it does 1/40 of job in 1 minute,
Pump B ----------- 60 minutes draining
so it does 1/60 of the job in 1 minute.
..
1/40 -1/60 is the job done in 1 minute when both are open
..
(60-40)/2400= 20/2400====> 2/240======> 1/120 of the job
..
so it will take 120 minutes to fill the pool.

m.ananth@hotmail.ca
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