UPSC Prelims 2001·GS1·science-and-technology·science and technology

Water is filled in a container in such a manner that its volume doubles after every five minutes. If takes 30 minutes for the container to be full, in how much time will it be one fourth full?

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UPSC Civil Services preparation
Last updated 23 May 2026, 3:31 pm IST
  1. A7 minutes and 30 seconds
  2. B10 minutes
  3. C20 minutesCorrect
  4. D25 minutes

Explanation

To solve this problem, we need to work backward from the time the container is full. The volume of water doubles every five minutes. This means that five minutes before the container was full, it must have been half full. The container is full at 30 minutes. Therefore, it was half full five minutes earlier, at 25 minutes. Following the same logic, five minutes before it was half full, it must have been one fourth full. Subtracting another five minutes from 25 minutes gives us 20 minutes. The container was one fourth full at 20 minutes.
science-and-technology: Water is filled in a container in such a manner that its volume doubles after every five minutes. If takes 30 minutes fo
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