A wizard possesses two magical wands. The first wand burns from end to end in exactly 48 minutes, but it burns at an uneven, non-linear rate. The second wand burns in 24 minutes, also at an irregular rate. How can the wizard use these two wands to time an exact interval of 36 minutes?
Light the first wand from both ends, and light the second wand from one end simultaneously.
Lighting the first wand from both ends makes it burn out in 48 / 2 = 24 minutes, regardless of its uneven burning rate. When it burns out at 24 minutes, immediately light the unlit end of the second wand. Since the second wand has 24 minutes total capacity and has burned for 24 minutes from one end, lighting the other end causes it to burn out in 24 / 2 = 12 more minutes. Total time: 24 + 12 = 36 minutes.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Hard. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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