A tank can be filled by pipe A in 2 hours and pipe B in 6 hours. At 10 am pipe A was opened. At what time will the tank be filled if pipe B is opened at 11 A.M. ?

1/2+1/6

=3+1/6

Pipe A will fill 3 units till 11 am.

Remaining capacity = 6−3=3 units

Now both pipes will fill the tank in

T.C/efficiency=3/(3+1)=3/4hours

So,(11+3/4)am, tank will be filled

=11:45 A.M