Pipes & Cisterns · Question 7 · Medium
Pipes & Cisterns question 7
Pipes A and B fill a tank in 20 minutes and 30 minutes respectively, and pipe C empties it in 15 minutes. If all three are opened on an empty tank, how long will it take to fill?
- 30 minutes
- 60 minutes
- 12 minutes
- 45 minutes
Answer and explanation
Answer: B. 60 minutes
Explanation: Net rate = 1/20 + 1/30 − 1/15 = (3 + 2 − 4)/60 = 1/60, so 60 minutes.
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