Q. Pipe A can fill a tank in 20 hours and pipe B can empty it in 40 hours. If both are opened together, how long will it take to fill half the tank?
✅ Correct Answer: (B)
20 hours
Explanation: Net rate = 1/20 − 1/40 = 1/40 → half tank in 20 hours.
Explanation by: Hriday
Net rate = 1/20 − 1/40 = 1/40 → half tank in 20 hours.