- A12 h 40 min
- B13 h
- C12 h
- D13 h 30 min
Step-by-Step Solution
In 18ths: A 3, B 2, C −1; one 3-hour round gives 4. After 4 rounds (12 h): 16; A needs 2 of its 3 → 40 min. Total 12 h 40 min.
Answer: A) 12 h 40 min
Pipe A fills a tank in 6 hours, pipe B in 9 hours, and pipe C empties it in 18 hours. They work one at a time for an hour each in the order A, B, C, A, B, C, … on the empty tank. When is the tank first full?
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