Fuses

Written on 1:01 am by Vja Students

You have two slow-burning fuses, each of which will burn up in exactly one hour. They are not necessarily of the same length and width as each other, nor even necessarily of uniform width, so you can't measure a half hour by noting when one fuse is half burned. Using these two fuses, how can you measure 45 minutes?


Ans:
Light one fuse at both ends and, at the same time, light the second fuse at one end. When the first fuse has completely burned, you know that a half hour has elapsed, and, more relevantly, that the second fuse has a half hour left to go. At this time, light the second fuse from the other end. This will cause it to burn out in 15 more minutes. At that point, exactly 45 minutes will have elapsed.

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2 Comments

  1. PuRaV |

    Make twelve equal pieces of any of the coil so ull get 5 minuts sections now burn nine parts and get 45minuts

     
  2. Anonymous |

    Suppose we have fuses A,B.

    1. Burn A from one side and burn B from both the side, B will finish in 30 min .
    2. Once B finishes ...burn A from other side as well...it will finsh in exactly 45 min.

     

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