Q. Pipe A can fill a tank in 6 hours. Pipe B empties it in 18 hours. If A works for 3 hours and then both are opened, how long will the tank take to fill completely?
✅ Correct Answer: (C)
6 hours
Explanation: A fills half in 3 hrs. Remaining filled at rate (1/6−1/18)=1/9 → total = 6 hrs.
Explanation by: Hriday
A fills half in 3 hrs. Remaining filled at rate (1/6−1/18)=1/9 → total = 6 hrs.