Question 1032764
Pipe A can fill the pool in 3 hours
It does 1/3 of the job in 1 hour


 and pipe B can drain it in 6 hours.
It does 1/6of draining job in 1 hour



 The caretaker opens pipe A at 6:00 every morning.

For 1/2 hour both were open.

In 1 hour 1/3 -1/6 of the job of filling is done

=1/6 

In 1/2 hour 
1/6*1/2 = 1/12 of filling is done

Balance filling will be 1-1/12 = 11/12 

Filling
It does 1/3 of job in 1 hour
so 11/12 of the job it will take

11/4 hours

Pool will get filled in 1/2 + 11/4 = 13/4 hours

3.25 hours

The pool will fill at 9:15 AM