Thursday Thinker 07/09/17 – Answer!

a photo of The Sculpture of The Thinker

As we slowly make our way to the weekend I thought it would be fun to give you a puzzle to work out. No prizes, it is just for fun.

The Puzzle

You wake up in front of a room with one lightbulb inside it. The door is shut so you can’t see if the light inside. By the entrance to the room there are 3 switches, all in the ‘off’ positions. You can flick the switches as much as you want before you enter the room, but once you open the door, you can’t touch them. How do you know which lightswitch operates the lightbulb?

Did you work it out? Answer below!

The Answer


Turn 2 switches ‘on’ (leaving 1 switch ‘off’) and wait a minute. Just before you enter the room, turn one switch from ‘on’ to ‘off’. Once inside, touch the lightbulb. If the lightbulb is warm, but the light is off, it has to be the last switch you turned ‘off’. If the lightbulb is cold and is off, it has to be the switch you left ‘off’ and haven’t touched. Finally, if the lightbulb is on, it has to be the switch left ‘on’.

Easy? What did you think? Let me know in the comments below. 🙂

George Carlin Quote "Think of how stupid the average person is then realise half of them are stupider than that."



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