SOLUTION: A tank can be filled in 18 hours by pipe A alone and in 22 hours by pipe B alone. How long will it take to fill the tank if both pipes are working?

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Question 578599: A tank can be filled in 18 hours by pipe A alone and in 22 hours by pipe B alone. How long will it take to fill the tank if both pipes are working?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Filling the pool is one job
Pipe I 18 hours
It does 1/18 of the job in 1 hour
Pipe II 22 hours
It does 1/22 of thejob in 1 hour
together they will do 1/18 + 1/22 of the job in 1 hour
Take the LCD
(22+18)/22*18
40/396
=10/99 of the job they complete in 1 hour
so they will take 99/10 hours
= 9.9 hours
OR 9 hours & 54 minutes ( 0.9 *60 = 54)