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#71325 - 10/26/06 02:16 PM Brain teaser
Rewired Offline
Member

Registered: 01/01/06
Posts: 567
Loc: Hamilton, Ontario, Canada
This one was told to me by a plumber today at the jobsite. Its easy I figured it out

You have 3 lights up in the attic of a building. These 3 lights are controlled by 3 individual switches in the basement of the building. You must identify which switch controls what light BUT, you can't obviously see the lights from the basement.
How do you identify what light is controlled by what switch without the use of any tools except maybe a stepladder if needed to reach the lights, and with only making ONE trip from the basement to the attic. Assume the lights could have just recently been on and might still be hot.



A.D

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#71326 - 10/26/06 02:33 PM Re: Brain teaser
rabbitgun Offline
Member

Registered: 07/25/06
Posts: 21
Aw! You should edit out your last sentence.

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#71327 - 10/26/06 02:40 PM Re: Brain teaser
Sixer Offline
Member

Registered: 08/08/05
Posts: 264
Loc: Canada
(the last sentence gave the clue)

I deleted my post so others can have a chance at guessing it.

[This message has been edited by Sixer (edited 10-26-2006).]

[This message has been edited by Sixer (edited 10-26-2006).]
_________________________
Sixer

"Will it be cheaper if I drill the holes for you?"

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#71328 - 10/26/06 04:18 PM Re: Brain teaser
Bob Offline
Member

Registered: 02/05/02
Posts: 182
Loc: Mobile, AL, USA
Turn sw#1 on and leave it on for 1 minute.
Then turn it off.
Turn on sw#2 and leave it on.
Goto attic and climb ladder.
Feel the off bulbs. The hot one is on sw#1
and the other is on sw#3.

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#71329 - 10/26/06 04:35 PM Re: Brain teaser
e57 Offline
Member

Registered: 05/27/03
Posts: 2837
Loc: S.F.,CA USA
I heard this one on Car Talk....
_________________________
Mark Heller
"Well - I oughta....." -Jackie Gleason

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#71330 - 10/26/06 04:39 PM Re: Brain teaser
Surfinsparky Offline
Member

Registered: 07/29/05
Posts: 77
Loc: merritt island fl usa
Step 4 re-wire lights to one switch and locate switch near attic access!!

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#71331 - 10/26/06 07:31 PM Re: Brain teaser
JoeTestingEngr Offline
Member

Registered: 11/04/05
Posts: 786
Loc: Chicago, Il.
It was an easy solution but I started wondering how MacGyver would've done it. I'm pretty sure he would've started by taking apart the clothes dryer. He might also have left the switch on and looped a string with a weight, secured to the rafter, around the handle. The can of spray starch would act like a blow torch ,(see also: James Bond, "Live and Let Die" venomous snake application), on the string. This would create a precise, for MacGyver, time delay, allowing ample transit time to the attic. Now, if he can only help Dana Elcar grow his hair back and get him to stop picking on Pappy Boyington!
Joe

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#71332 - 10/27/06 10:08 AM Re: Brain teaser
Alan Belson Offline
Member

Registered: 03/23/05
Posts: 1801
Loc: Mayenne N. France
One of the bulbs has been 'borrowed' by a sheetrocker: How many trips to the attic do you need to do to be 100% sure which switch operates which bulb?

Alan
_________________________
Wood work but can't!

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#71333 - 10/27/06 10:52 AM Re: Brain teaser
Dnkldorf Offline
Member

Registered: 12/12/04
Posts: 1091
Loc: nowhere usa
Make one trip up there and install a camera?

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#71334 - 10/27/06 01:51 PM Re: Brain teaser
wa2ise Offline
Member

Registered: 11/29/02
Posts: 773
Loc: Oradell NJ USA
 Quote:
One of the bulbs has been 'borrowed' by a sheetrocker: How many trips to the attic do you need to do to be 100% sure which switch operates which bulb?


Well, if neither of the two remaining bulbs is on, but one is warm, the missing bulb must be the one that's "on". Vefify by taking one of the two remaining bulbs to try it in the empty socket, it should light. You don't have to leave the attic. One trip

Or if one is on, and the other is warm, then the missing bulb is the one that was always off. Or if the dark bulb is cold, then the missing bulb was the one that would have been warm. One trip

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