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Originally posted by: Darth Simon
There are three light bulbs in a room, and three light switches outside the room. You are outside, and want to match up which switch goes with which light bulb. You can only travel into the room once, and cannot come back in again. You can do anything you want upon entering the room. How can you set the situation so that you will know which switch goes with which light bulb?

I think I've got the answer. Turn two switches on, wait 5 minutes, turn one off. Enter the room. One will be on, that's the on switch. One will be off and cold - that the switch you didn't touch. One will be off and hot - that's the one you just turned back off before entering.