There are 3 switches at one end of the long corridor and small room behind closed at another end. Room has a conventional light bulb controlled by one of the switches. You start with all switches been off. How many trips to that closed room is needed to find which switch is actually controls bulb?
--
Note: Comments may have spoilers! Come up with solution on your own before reading them.
Posts
2 comments:
Just one trip is sufficient! You turn on Switch #1 for a couple of minutes. Then you turn off Switch #1 and turn on Switch #2. You visit the closed room: If the lamp is lighting it is Switch #2. If it is off but warm then it is Switch #2. If it is off and cold then it is Switch #3.
You are right!
Post a Comment