You have two fuses (a fuse is something you burn to eventually set off an explosive), one which burns 1 hour and one which burns 2 hours. The fuses do not burn at a constant rate, so, for example, the last few inches of the first fuse could take 5 minutes or 55 minutes to burn. You have as many matches as you want. With these fuses, you have to measure a time period of exactly 45 minutes. How do you do this?
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2 guesses to Short Fuse |
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August 18th, 2010 | Category: 
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Fuse A = 1 hour
Fuse B = 2 hours
We burn Fuse A on both ends at the same time (it will burn for 30 minutes now), and at the same time, we burn Fuse B on one end.
When Fuse A burns out, Fuse B will have 90 minutes remaining.
All we need to do now, in order to measure 45 minutes, is to burn the rest of Fuse B on both ends!
PS: I’m assuming we are not required to measure 45 Minutes from the “start” of the experiment.
Great job, Rool.
You explained it perfectly.
You’re today’s winner.