Riddle: A man headed for a particular destination drove till he reached a 'Y' junction.He stood there confused hesitating whether to go right or left till he located two men,A and B resting under a tree.A ALWAYS spoke the truth while B ALWAYS lied.Both of them knew which road to take to reach the destination the man wanted to.The man had only ONE chance of choosing any ONE of the men,A or B,and he could ask the man he chose only ONE question to procure his answer.He did not know which of them spoke the truth and which lied.
The man went forward,randomly chose one of the two men,asked him only one question,got his answer and drove away to his destination.
What question did he ask?
Answer: Attention guys!! This is a little complicated and demands some time and concentration to be understood.
The question the man posed to the man he chose(either A or B) was:"If I asked your partner which road to take,what would his answer be?"
The man would always take the road opposite to whatever answer he received.
Case 1. Let's suppose he chose A. A always speaks the truth.The question put to A is :"If I asked your partner which road to take,what would his answer be?" Now A's partner is B who always lies.Hence A being truthful would answer what B would have answered,which would be the wrong road since B would lie.Therefore the man would take the road opposite to the answer he received.
Case 2. Let's suppose he chose B. B always lies.The question put to B is :"If I asked your partner which road to take,what would his answer be?" Here,B's partner is A who always spoke the truth.Had A been asked which road to take he would have answered correctly,and B,knowing that,would provide the man with the incorrect answer.Hence the man would again have to take the road opposite to whatever answer he received.