## Sunday, October 18, 2009

### The Lightbulb Puzzle

Here is a good old puzzle that was also featured in a recent Spanish thriller "Fermat's room". Characters had only one minute to solve this puzzle before room walls would smash then dead:

There is a sealed room containing one light bulb. Outside of the room there are three switches, only one of which operates the bulb. You can turn switches On and Off in any way you see it fit. How can you guess which switch operates the bulb in the room, if you could only open the door and look inside the room once?

To know more about "Fermat's Room" movie and other breathtaking Math Adventures, read this recent story from TheMathMom.

Submit your answer on our Family Puzzle Marathon site. Solve three puzzles and get a prize!

Kim said...

Are you allowed to flick a switch while it's open?

Maria said...

No. You flip as many switches as you wish while it is closed. Then you open the door and decide what switch is connected to the light bulb.

Claire said...

Ok, I'm standing outside the door... I flip switch one, and let it stay up for about 10-15 minutes. flip off switch one, then flip switch 2. Open the door... is the light on? Then switch 2 operates the bulb... if the light is not on, touch the bulb (is this possible?) - is the bulb warm? Then it was switch one. If the bulb is neither warm nor on... either it's switch three or the bulb needs to be replaced. :) (ok, the last lil bit there - about the burnt out bulb - was just funny stuff... but the rest, I meant)

how did I do?

Maria said...

Wow, Claire!
This is very very impressive.
Few people are able to solve this without any hints.

Second puzzle for Claire!

check for a new puzzle tomorrow