Friday Puzzle Answer

Since I’m in the mood and because I’m not allowed to post answers there, I’ll take a crack here at answering Richard Wiseman’s Friday puzzle this week, which reads thusly:

There’s a standard filament-type light bulb in a closed room upstairs. It is controlled by one of three standard on-off switches downstairs. You are downstairs. How can you discover for certain which switch controls the light by operating one or more switches and then taking only one trip upstairs into the closed room?

Answer after the fold.

I say I turn on one switch and wait a few minutes then turn it off and turn on the next one. I go upstairs and if the bulb is off and hot, it was the first one. If it is on, it was the one I just flipped. And if it is neither, it’s the third one.

Are there any other possible answers?

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One response to “Friday Puzzle Answer

  1. Wow… i can’t thik of a better one than that.

    And I think I might have thought of that answe… maybe… after a long time… and some cheating….