SOLUTION: one pipe can empty the tank in 4 hours. a second pipe takes 2 hours to do the same job. how long will it take to empty the tank if both pipes are open?

Question 631672: one pipe can empty the tank in 4 hours. a second pipe takes 2 hours to do the same job. how long will it take to empty the tank if both pipes are open?

Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
one pipe can empty the tank in 4 hours. a second pipe takes 2 hours to do the same job. how long will it take to empty the tank if both pipes are open?
.
Let x = time (hours) it takes for both
then
x(1/4 + 1/2) = 1
x(1/4 + 2/4) = 1
x(3/4) = 1
x(3) = 4
x = 4/3 hours
or
x = 1 and 1/3 hours
or
x = 1 hour and 20 minutes
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