| Title: | Mathematics at DEC |
| Moderator: | RUSURE::EDP |
| Created: | Mon Feb 03 1986 |
| Last Modified: | Fri Jun 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 2083 |
| Total number of notes: | 14613 |
You are in a room with 3 switches. Next to you there is a room with 3 lamps, but you can't see them. Each switch turns on and off one lamp, but you don't know which. Initially all the lamps are turned off. You are allowed to do anything you want with the setting of the swicthes. Then you must go to the other room and decide there which switch controls which lamp.
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 1736.1 | FORTY2::PALKA | Mon Mar 29 1993 10:21 | 13 | ||
This sounds like a good question for the brain_bogglers conference.
Here's an answer
You turn two lights on. Wait 5 minutes and turn one off again.
Then go to the other room.
The light which is still on is controlled by the switch you left on.
Now touch the bulbs of the other 2 lights. One will be warm - this is
the one controlled by the switch you turned on and then off. The other
is cold - this is controlled by the switch you didn't touch.
Andrew
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