Question

it takes 12 hrs to fill a swimming pool using two pipes . If the pipe of larger diameter is used for 4 hrs and the pipe of smaller diameter is used for 9 hrs , only half of the pool is filled . How long would each pipe take to fill the pool

Answer 1

hope so it will help u a lot.......
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.

Hence the 1 pipe would take 20hours and the 2 pipe would take 30 hours