Beach Day by Rodger Bliss
December 2023

Short Fuse

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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  • Roolstar

    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.