Question

A tank can be filled in `2  2/5` hours when all the five pipes (including both inlet and outlet pipes) are turned on simultaneously. Also, it is given that each inlet pipe can fill the tank in 4 hours when working separately and each outlet pipe can empty the tank in 6 hours. when working separately. How many outlet pipes are attached to the tank?

Options

• 1

• 4

• 2

• 3

Answer 1

2

Explanation:

Work done In 1 hour by all five pipes = `1/(12/5) = 5/12`

Let there be 'n' inlet pipes, hence no. of outlet pipes = 5 - n

Now, `1/4 ("n") - 1/6(5 - "n") = 5/12`

`=> "n"/4 - 5/6 + "n"/6  5/12`

`=> (5"n")/12 = 5/12 + 5/6  "or"  15/12`

n = `(12 xx 15)/(12 xx 5)` = 3 

Hence, there are 3 inlet and 2 outlet pipes.