Thought Exercises


Dr T
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You are walking down a road and you encounter a fork in the road and you do not know the correct way to go. There are two men standing at the junction and both know the correct road. One man always lies, and the other man always tells the truth, but you do not know who is the liar and who is the one who tells the truth. You can only ask each man one question, but it must be the same question for both. What is the question that would allow you to get the information necessary to choose the correct path?

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OK, lets try those:

'If I ask him, will he give me the correct answer?' They would both say "no" now what? Which road do we take Push?

it could be 'If I asked him, would he say Yes?' simlarly, the question remains, for me, which road to follow based on the answer to this question.

On the right track. :)

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Ok Dr. My last try...you ask both:

'If I asked him, which road would he tell me to go by?'

They ought to both answer the same road, because the one telling the truth will say the correct one, and the other will try to tell you a lie about what the other would say? Am I getting nearer, or just confusing it even more!! lol.

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This is a classic, most memorably seen in the movie Labyrinth. Ask one of the men which way the other would say you should go. Whichever he says, the other way is the correct one. If the one you ask is the liar, he'll lie about what the other would say, but if he is the truthful one, he'll tell you what the other would say, which would be a lie. :lol:

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Just trying to get my explanation more clear:

The one telling the truth, when asked which road the other would tell you to use, would tell you the INCORRECT road, because the one lying would tell you that.

The one lying, when asked which road the truthful person would reply, would also tell you the INCORRECT road, as he cannot tell you the truthful answer that the other would say....therefore, whichever answer they both give should be the same one and you should take the opposite road?

Oops, sorry Outshined...I didn't refresh my page before adding my explanation of my post!!!

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In the basement there are 3 light switches in the off position. Each switch controls 1 of 3 light bulbs on the floor above. You may move any of the switches, but you may only go up stairs one time. How can you determine which switch controls each light?

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In the basement there are 3 light switches in the off position. Each switch controls 1 of 3 light bulbs on the floor above. You may move any of the switches, but you may only go up stairs one time. How can you determine which switch controls each light?

Get someone to help you! :P

M.

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Are you allowed to move the switches a number of times, or just once each? Can you see the bulbs that they are controlling from the bottom of the stairs, or are they in different rooms?

I would be looking for the light coming out from the rooms in which the bulbs were placed, but I doubt that is the correct solution.

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