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#1 2007-05-28 01:48:43
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- Registered: 2007-05-28
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Bulb Problem
One good brain teaser
There is a bulb on first floor and switch is at ground floor . You can not see the bulb or light from that bulb from ground floor. You can not tell from ground floor if the bulb is on or off.
There are three switches on ground floor. Out of these three switches one belongs to the bulb at first floor.
You need to find out correct switch, but you are allowed to go only once at first floor .
Can you guess how to solve it ?
?????
?????
PB
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#2 2007-05-28 02:41:32
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- Registered: 2007-04-18
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Re: Bulb Problem
What you do I think, is that you flick the 1st switch, then turn it off and flick the 2nd switch, leaving the 2nd switch on. Then, go upstairs and check on the lightbulb. If the lightbulb is on, then obviously the 2nd switch is correct. If the lightbulb is off, but still hot, then it is the first switch. If the lightbulb is off and cool, then it must be the 3rd switch.
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#3 2007-05-28 13:20:22
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Re: Bulb Problem
What you do I think, is that you flick the 1st switch, then turn it off and flick the 2nd switch, leaving the 2nd switch on. Then, go upstairs and check on the lightbulb. If the lightbulb is on, then obviously the 2nd switch is correct. If the lightbulb is off, but still hot, then it is the first switch. If the lightbulb is off and cool, then it must be the 3rd switch.
that is right .
cheers
PB
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