Question

It takes 12 hours to fill a swimming pool completely using two pipes of different diameters. If the pipe of larger diameter is used for 4 hours and the pipe of smaller diameter is used for 9 hours, then only half of the pool is filled. How long will it take for each pipe to fill separately?

Answer 1

Answer:

the solution would be like this:-

let the time taken by the 1 pipe be x hours and let the time taken by the 2 pipe be y hours.

& the in 1 hour the 1 pipe can fill it=1/x

the in 1 hour the 2 pipe can fill it=1/y

1/x +1/y = 1/12 -1

4/x = 9/9 =1/2 -2

let 1/x be a and 1/y be b.

a+b= 1/12 -3

4a + 9b = 1/2 -4

multiply 3 by 4 and then subtract 5 and 6.

4a +4b=1/3 -5

4a + 9b = 1/2 -6

we get, b=1/30

y=30.

sustituting the value of y in eq. 3

a+1/30=1/12

x=20

hope it helps