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Q12 (CISF/2019) Science & Technology › Basic Science (Physics, Chemistry, Biology)

A water tank can be filled by a pipe in 4 minutes and by a smaller pipe in 12 minutes. If both the pipes are opened simultaneously, in how much time will the tank be filled?

Result
Your answer: —  ·  Correct: C

Explanation

To find the time taken when both pipes are opened simultaneously, we calculate their combined rate of work:

  • Rate of the first pipe = 1⁄4 tank per minute
  • Rate of the smaller pipe = 1⁄12 tank per minute

Combined rate = 1⁄4 + 1⁄12

To add these fractions, we use a common denominator (12):
Combined rate = 3⁄12 + 1⁄12 = 4⁄12 = 1⁄3 tank per minute.

The total time taken to fill the tank is the reciprocal of the combined rate:
Time = 1 ÷ (1⁄3) = 3 minutes.

Therefore, if both pipes are opened together, the tank will be filled in 3 minutes.

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SIMILAR QUESTIONS

CAPF · 2017 · Q79 Relevance score: 7.11

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