A pipe can fill the tank in ‘a’ hours and othr can empty in ‘b’ hours. If they open together, they can fill the tank in (b>a)

Correct Answer: (ab/b−a)hrs.

The first pipe can fill the tank in ‘a’ hours.

The first pipe can fill in one hour = 1/a part

The second pipe can empty the tank in ‘b’ hours

I one hour, the II pipe can empty = 1/b part

If both the pipes are opened together, in one hour they fill

1/a−1/b=b−a/ab

The tank can be filled in (ab/b−a) hours