Feb 16
A prisoner is escaping from jail. At some point on his path, he is arriving at a crossing. He can take either the road to the left or the one to the right. One will lead him to freedom while the other back to jail. He does not know which one. On each side of the road, there is a guy waiting. The prisoner knows that one of them is honest while the other is not. The prisoner is allowed to ask just one question to one of them, in order to find his way. What is the right question to ask?
February 17th, 2007 at 11:50 am
I’d go for “Are you the honest guy?”. The honest guy would probably answer “What?”, while the other would go for Yes.
February 17th, 2007 at 4:27 pm
I am not sure it would work. Because the honest guy would answer yes, because he is, the other one yes as well, because he isn’t, so he is lying.
In addition, you don’t know where to go afterwards.
February 25th, 2007 at 9:29 pm
I would ask “Which way will the other guy tell me to go if I want to be free?”
The honest guy will point the way to jail.
The dishonest guy will also point to the way to jail.
Go the other way.
February 25th, 2007 at 9:33 pm
Sorry, but I have to add that my answer (previous post) only works if the dishonest guy ALWAYS lies. Most dishonest people do tell the truth at least once in a while.
February 25th, 2007 at 10:39 pm
Hi Remon,
Yeah, I think you are right. I would also ask something like ‘Which way would the other guy point as leading to freedom.
But of course, as you point out, this can work only if the honest guy always tell the truth and the other one always lies (or more generally if one of them tells the truth while the other one would lie). But I think there is no solution otherwise, is there?
Cheers,