SOLUTION: a water tank has an inlet pipe (to fill the tank) and an outlet pipe (to empty the tank). the tank will fill in 8 hours when both pipes are open. if it takes2 hours longer to empty

Question 354012: a water tank has an inlet pipe (to fill the tank) and an outlet pipe (to empty the tank). the tank will fill in 8 hours when both pipes are open. if it takes2 hours longer to empty the tank than it does to fill the tank, how long does it take the outlet pipe to empty the tank?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
let it take x hours to fill the tank when inlet alone is open
it does 1/x of the job in 1 hour.
..
it will take (x+2) hours to drain when only drain is open
..
so 1/(x+2) of the job is done in 1 hour
..
it takes 8 hours to do the job when both are open
1/x-1/(x+2)= 1/8
x+2-x / x(x+2)=1/8
2/x(x+2)=1/8
16=x(x+2)
16=x^2+2x
x^2+2x-16=0
solve using quadratic formula
determinant = 68
-2+sqrt68 /2
=3.1
x=3.1
draining = 3.1+2 =5.1 hours
..
m.ananth@hotmail.ca
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