Three pipes, A, B, and C are capable of filling a tank in 6, 8, and 12 hours,…
2025
Three pipes, A, B, and C are capable of filling a tank in 6, 8, and 12 hours, respectively. When all three pipes are opened together, they operate for 2 hours before pipe C is closed. How much additional time will it take to completely fill the tank after that?
- A.
6/7 hours
- B.
1/7 hours
- C.
3/7 hours
- D.
4/7 hours
Attempted by 32 students.
Show answer & explanation
Correct answer: A
1. (1/6 + 1/8 + 1/12) = 9/24 = 3/8 per hr.
2. In 2 hrs: 2 * 3/8 = 6/8 = 3/4. Remaining = 1/4.
3. Pipe A+B = 1/6 + 1/8 = 7/24 per hr. Time = (1/4) / (7/24) = 6/7 hours.