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RE: Brainteaser

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1. Flip the first switch on for 10 min +/- 30 second.  8^)
2. Flip the first switch off.
3. Flip the second switch on
4. Go up stair right away
5. If the light is on, the second switch control the light
6. If not, touch the light bulb
7. If it is hot, the first switch control the light
8. If it is cool, the third switch control the light



Frank Yang, P.E.           
Senior Engineer                                   BERGER/ABAM Engineers Inc
Voice: 206-431-2374                                33301 Ninth Avenue South
Fax:   206-431-2250                             Federal Way, WA  98003-6395
e-mail: yang(--nospam--at)                         

-----Original Message-----
From:	lsmith(--nospam--at) [SMTP:lsmith(--nospam--at)]
Sent:	Friday, April 24, 1998 5:26 AM
To:	seaoc(--nospam--at)
Subject:	Brainteaser

OK, this has nothing to do with engineering, but you do need to think to
figure it out, so, I believe we all qualify.  According to a friend of
mine, this was a question from a MENSA test:

There is a switchplate with three (3) switches in the basement of a house.
Up the stairs in a room on the ground floor is a light bulb.  The new owner
of the house knows that the light bulb is controlled by one of the three
switches and is in the basement.  With only one trip up the stairs, how can
the new owner determine which switch controls the light bulb?