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Practice mode Pipes and Cistern

An inlet pipe fills a cistern in 20 minutes and an outlet pipe empties it in 30 minutes. If both are opened on an empty cistern, when will it be full?

Correct answer D. 60 minutes

Explanation

The outlet works against the inlet, so net rate = 1/20 − 1/30 = 1/60 of the cistern per minute, and it fills in 60 minutes.

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Question 03 Pipes and Cistern

How long will it take to empty the tank if both the inlet pipe A and the outlet pipe B are opened simultaneously? I. A can fill the tank in 16 minutes. II. B can empty the full tank in 8 minutes.

Correct answer B. II alone sufficient while I alone not sufficient to answer

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Question 04 Pipes and Cistern

How much time will the leak take to empty the full cistern? I. The cistern is normally filled in 9 hours. II. It takes one hour more than the usual time to fill the cistern because of la leak in the bottom.

Correct answer B. II alone sufficient while I alone not sufficient to answer

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