Question

Pipe a can fill a tank in 20 hours while pipe b alone can fill it in 30 hours and pipe c can empty the full tank in 40 hours. If all the pipes are opened together half the tank will be filled in:

Answer 1

Answer:

8 4/7 hrs

Step-by-step explanation:

{(1/20 + 1/30) - 1/40}

= {5/60 - 1/40}

= 7/120

so time will be taken to fill the half tank is

120/7 x 1/2

= 8 4/7 hrs