A water tank is two-fifth full. Pipe A can fill a tank in 10 minutes and pipe B can empty it in 6 minutes. If both the pipes are open, how long will it take to empty or fill the tank completely?
Q1. A water tank is two-fifth full. Pipe A can fill a tank in 10 minutes and pipe B can empty it in 6 minutes. If both the pipes are open, how long will it take to empty or fill the tank completely?
Answer: 6 min. to empty
Explanation: Pipe B empties faster than A fills; net drain rate = 1/6 − 1/10 = 1/15 of the tank per minute. To empty 2/5 of the tank takes (2/5) × 15 = 6 minutes.