- A8
- B12
- C10
- D6
Step-by-Step Solution
Second pipe runs 18 min filling 18/30 = 0.6. First must fill 0.4, so t/20 = 0.4 and t = 8 minutes.
Answer: A) 8
Two pipes can fill a tank in 20 minutes and 30 minutes respectively. Both are opened together, but the first pipe is closed after some time so that the tank is exactly full in 18 minutes. After how many minutes was the first pipe closed?
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