SOLUTION: a pump can pump out water from a tank in 11 hours. another pump can pump out water from the same tank in 20 hours. how long will it take both pumps to pump out the water in the ta

Question 513681: a pump can pump out water from a tank in 11 hours. another pump can pump out water from the same tank in 20 hours. how long will it take both pumps to pump out the water in the tank?
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
a pump can pump out water from a tank in 11 hours. another pump can pump out water from the same tank in 20 hours. how long will it take both pumps to pump out the water in the tank?
.
Let x = time (hours) it takes for both
then
x(1/11 + 1/20) = 1
multiplying both sides by 220:
x(20 + 11) = 220
x(31) = 220
x = 220/31
x = 7.1 hours
or
x = 7 hours and 6 minutes

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