Two pipes A and B can each fill a tank in 40 and 60 min, respectively. There is an outlet C. If all the 3 pipes are opened up, the tank will be filled in 30 min. How much time will it take for C alone to empty the full tank?
Correct Answer: 2 h
Explanation:
Work done by C in one min = (1/40 + 1/60) - 1/30 = 1/120
Hence, C can empty the tank in 120 min or 2 h.
