Pipes A and B fill a tank in 5 and 6 hours respectively. Pipe C empties the tank in 12 hours, if you open all the three pipes together this tank will be filled in?
Answer: A
It is given that Pipe A,B and C work simultaneously.
Pipe A and B are filling the tank and Pipe C is emptying it.
In 1 hour volume of tank filled by Pipe A: 1/5th
In 1 hour volume of tank filled by Pipe B: 1/6th
In 1 hour volume of tank emptied by Pipe C: 1/12th
Working together Pipe A B and C fill x volume of tank.
=>1/x = (1/5)+(1/6)-(1/12)
=>x=60/17 hours