My friend's brother recently went for grad school interviews, and he got asked the same question at more than one institution. I found this question quite fun, so I'm posting it here for you guys *g*
A little background, my friend's brother majors in Civil Engineering, though the question itself is a basic physics question and has nothing to do with Civil Engineering. It's actually not that hard, I'm sure a lot of you will get it ^^ It just sounds a lot more confusing than it actually is. Okay, here goes:
There is a shut room with three light bulbs. Outside of the room, there are three switches, one for each light bulb. You can do whatever you want to/with the switches outside, but you can only walk into the room once. (And you have to close the door behind you.) With this in mind, what will you have to do to be able to tell me which switch lights up which bulb after going into the room only once?
AND NO, YOU CANNOT CALL YOUR FRIEND WHEN YOU ARE INSIDE THE ROOM SO S/HE COULD TURN THE SWITCHES ON/OFF FOR YOU. (ok, I admit, that was the first thing I thought of and I got called a rottten cheat *evul cackling*)