# Two pipes A and B can fill a tank in 60 minutes and 75 minutes respectively

Two pipes A and B can fill a tank in 60 minutes and 75 minutes respectively. There is also an outlet C. If A, B and C are opened together, the tank is full in 50 minutes. How much time will be taken by C to empty the full tank?
(a) 100 minutes
(b) 110 minutes
(c) 120 minutes
(d) 125 minutes

Anurag Mishra Professor Asked on 19th February 2016 in

Answer: (a) 100 minutes

Solution:-
A pipe can fill a tank = 60 minutes
Therefore, A pipe can fill a tank in minute = 1/60

B pipe can fill a tank = 75 minutes
Therefore, B pipe can fill a tank in a minute = 1/75

A, B and C together can fill a tank = 50 minutes
Therefore, A, B and C can fill a tank in a minute = 1/50

Thus, C pipe can empty a tank in minute = 1/50 – (1/60 + 1/75)
= {6 – (5 + 4)}/300
= -3/300
= 1/100

Therefore, C pipe can empty same tank = 100 minutes.

Hence, the correct answer is option (a) 100 minutes.

Anurag Mishra Professor Answered on 19th February 2016.