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Light The Cords Problem

Your job is to measure 45 minutes, if you have only two cords and matches to light the cords.

1. The two cords are twisted from various materials and so their different segments can burn at different rates.
2. Each cord burns from end to end in exactly one hour.

Describe your way of measuring the 45 minutes.

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  1. Light it from one end. When it burns out half the length, light it form the other end. Should give 45 min

  2. Light one cord at one end and the other at both ends. When the cord lit at both ends burns out (t1=30 min), light the other cord at the second end. When this cord burns out (t2=15 min), you will have precisely 45 minutes elapsed (t1+t2=45 min).

  3. Absolutely correct