Wednesday, October 3, 2012

Two guards riddle - one will always lie

You are imprisoned in a chamber with two doors as the only exit. One door leads to death by cancer, filled with complications and malpractice; the other door leads to riches of jewelry, money and fine clothing for the rest of your life. There are two guards standing before you: one guard always lies; the other always tells the truth. Of course, you don’t know their identities. You can ask only one question to save your life. What should you ask?



Solutilon :
This is a logic question and can be answered if one realizes that the TRUTH of a LIE is a LIE, and the LIE of a TRUTH is a LIE. You need one guard to give you the other guard’s answer. Knowing this one could ask a question like, “If I were to ask the other guard which door leads to freedom, what would he say?”


If you ask the guard who always tells the truth, he would tell you the other guard would point you to the door of death. If you ask the guard who always lies, he would tell you the opposite door of the truth-telling guard and point you to the door of death. In either case, both guards will point to the door of death so you should choose the other one

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