Question

Please help me solve this question

Answer 1

Let the time taken by 1 pipe be x and other be x-3.

6hrs 40min = 20/3 hrs

According to question,

1 / x - 3 + 1 / x = 3/20

x + x-3 / x^2-3x = 3/20

2x-3 / x^2-3x = 3/20

Cross multiplication,

20(2x-3) = 3(x^2-3x)

40x-60 = 3x^2-9x

3x^2 - 9x - 40x + 60 = 0

3x^2 - 49x + 60 = 0

3x^2 - 45x - 4x + 60 = 0

3x ( x - 15 ) - 4 ( x - 15 ) = 0

x = 15

Therefore, time taken by 1st pipe = 15hrs

and second pipe = x-3 = 15 - 3 = 12hrs