Question

Pipes A and B are filling pipes while pipe C is an emptying pipe. A and B can fill a tank in 72 and 90 minutes respectively. When all the three pipes are opened together, the tank gets filled in 2 hours. A and B are opened together for 12 minutes, then closed and C is opened. The tank will be empty after :

• A. 12 minutes
• B. 15 minutes
• C. 18 minutes
• D. 16 minutes

Answer 1

Answer: (C)