(Close Window)
Topic: Three switches
Message: Posted by: thefifth (Aug 21, 2005 03:24PM)
There is a closet with one light inside. The closet is light proof. When the door is shut you cannot tell whether the light is on or off. Outside the closet there are three switches, and only one turns on/off the light bulb inside. You are allowed to play with the switches all you want. But you can only open the door once, and you are not allowed to play with the switches once you open the door. All the switches are in the off position and door is closed. Can you accurately tell which switch goes to the light inside?

I've just started posting here, if someone has already posted this puzzle I appologize. Have fun.
Message: Posted by: Scott Cram (Aug 21, 2005 04:18PM)
Simple. I'll label the switches A, B & C.

1) Flip switch A to the "ON" position for about one minute or so.

2) Flip switch A back to the "OFF" position.

3) Flip switch B to the "ON" position.

At this point, you immediately open the closet door.

If the light is on, it's obviously switch B that controls it.

If the light is off, but still warm, it's switch A that controls it.

If the light is off and isn't warm, it's switch C that controls it.
Message: Posted by: thefifth (Aug 21, 2005 04:22PM)
Very Good.