Can anyone help me... I don't even know where to begin????

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sareen

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Oct 9, 2009
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You have recently been hired to perform an important job.  Every evening you are to turn on the light in an interior room (a room with no windows to the outside) on the third floor of a building.  There is a bank of three switches in the lobby of the building just inside the front door.  One of these switches controls the light you need to turn on and the other two are not connected to anything.  You would like to figure out which switch controls the light and because you are inherently lazy you don't want to go up to the third floor to check whether or not the light is on more than one time.  Is it possible to determine which of the three switches controls the light if you check the light's status only once?

Assumptions:

     1.  You cannot see whether or not the light is on without going all the way up to the third floor (i.e. you can't go outside and see if light is shining through a window or look up the stairwell and see if light is shining under the door).

     2.  You know the light is off when you report for work the first evening.
 
Throw the first switch and then check. If the light is on, then you are done, if the light isn't on go back downstairs and throw the second switch, I f you don't here from your superiors, you know the second switch is the right one. If a call comes through to you inquiring why the light isn't on in the enclosed room, say it is your first day on the job and you forgot and then go and throw the third switch. Now you know what switch to throw everytime you go to work without having to go upstairs and check.
 
Or, if you can throw more than one switch at a time, throw all three switches, since two are duds and one is true, you'll know that the light is on without even having to go upstairs at all.
 
There's 3 floors and three switches. and one of the switch is for the third floor switch. So if you turn on the 1st and 2nd switch and you go upstairs to check the light. If the light is on, then obviously it is the 1st switch. If the light is not on then its the 3rd switch because the 3rd floor light is connected to 1st switch or the 3rd switch. Not the 2nd one.
 
Where do you get off assuming the second switch is for the second floor, when we are told that there are three switches, two are blank and one lights up the enclosed room on the third floor. The enclosed room could be on the 101st floor or the 51st floor for that matter.

Afterthought: If the light is not connected to the second switch, then why did you turn it on in the first place?
 
sareen, if there is a solution to this problem, we haven't seen it yet, unless you can throw more than one switch at a time.
 
You get the job at the downtown building, and one of your duties is to make sure the light is on in the enclosed room on the third floor. Your shift is from 3 PM to Midnight (hour for late lunch). Unknown to you the enclosed room is rented out to the mob where their accountant comes in every evening to cook the books. He enters the building by the rear entrance to avoid the public and leaves about 3 AM by the front door after he has laundered the mob's money to the Cayman Islands. As he leaves, he always turns off the third switch, the one that lights the enclosed room and pays no attention to the other two switches as he is ignorant of there utility. Hence, when you come in to work the second day, the first and second switches are in the on position and the third is in the off position. Ergo, you immediately know that the third switch is the one that lights the enclosed room (as you had turn all three switches to the on position the preceding day) and you proceed to turn it on and turn the two dummy switches off without ever having to go upstairs to check in the first place.
 
Lets see "watt" we can come up with.

Label the switches 1, 2, and 3.

1--Turn switch #1 on for a few minutes or so, then turn it off.
2--Turn switch #2 on and enter the room in question.
3--If the light is on, switch #2 operates the light.
4--If the light is off but warm, switch #1 operates the light.
5--Obviously, if the light is off and cool, switch #3 operates the light.
 
Good show TchrWill, I think you got it.

Afterthought: I had a similiar problem happen to me years ago, but it involved a black and white TV and when it was turned off the screen glowed for about five minutes.

What happen was this: I and a lady friend went looking for her son. We knock at where her son lived, but no answer. As she had a key, we went in and he was no where to be found, his black and white TV was turned off, but the screen was glowing. We found him under the bed.
 
What if the light in the room were those "Cool" LED lights - I am just kidding!! The base of those LED bulbs get warm enough......
 
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