Paul wrote:
Agent_777 wrote:
Ask them the question like this:
If I ask you whether the left road leads to place X, will you answer, yes?
In any case you"ll get the right direction.
If the one who lies says yes, then you would know that answer is no.
If the one who says the truth says yes, then you would know answer is yes. Now, in this instance, both of them said yes but outcome is different. Since you don't know which one you talked to, how would you know if it's the one, the one who lies or who says the truth, whom you talked to? Since outcomes are different, you cannot ask your question.
Actually I agree with Agent_777's qs.
Assume the road to left is indeed leads to X. Now if you ask the person who lies, the qs whether the left road leads to X, he has to answer 'No'. But the question is whether he will answer yes to this question. Again as he has to lie, he has to say 'yes'.
Ask the question to a person who tells the truth, he also will answer yes. Thus doesnt matter whom you ask, the answer will tell you whether the road to left leads to X.
Thus if the answer is yes, the road to left leads to X, if the answer is no, the road to right leads to X.