Legal Alien: A Scotsman in Montreal

Friday Fun!

Something to wrap your brain around....

You are standing in a room with three switches, which can either be ON or OFF, each of which controls a lightbulb in an adjacent room which you cannot see in any way. By manipulating the switches and exiting the room only the once (at which point the door shuts behind you and you can no longer see the switches), how do you tell which switch controls which bulb?