Question

Two pipes running together can fill a tank in 20 minutes.

If one pipe takes 9 minutes more than the other to fill it, find the time taken by each pipe to fill the tank.

Answer 1

45, 36

Explanation:

let x y minutes be the time for pipes to fill the tank, let n be the water needed to fill the tank.

x-y=9

(n/x)*20+(n/y)*20=n

n is removed by dividing the 2nd equation by n

here u get:

(1/x+1/y)*20=1

you sub x=9+y into the above equation

1/y+1/(9+y)=1/20

((9+y)+(y))*20=(9+y)(y)

180+40y=9y+y2

y2-31y-180=0

then use the quadratic formula and u will find y=36 or -5

-5 is rejected because it is negative

x=36+9=45

therefore it is 36 mins and 45 mins