Applied Maths. (ask a question or 50% to unfortunate end.??)

2008-10-10 3:26 pm

Dr. who is walking down a corridor when he comes to two dorrs, one to the left and one to the right. One door leads to where he wants to go, and the other leads to an unfortundate end. Fortunately, there are two beings who know all about the dorrs there also. Unfortunately, one of the beings always tells the truth, and the other always lies, and there is no way to tell which is whcih. The Doctor can ask only one question (with a 'left' or 'right' answer) to one of the beings to discove which way to go. Can you think of a suitable question, or is there a 50% chance that you will come to an unfortunate end?

Thanks.....if you read "The Pyramids of Mars" should be better....

回答 (1)

Uncle Michael

2008-10-10 8:15 pm

✔ 最佳答案

The question should be:
”What is the other one’s answer if I choose a door to where I want to go?”

The action should be:
Refer to the answer. Choose the alternative door.
(If the answer is ‘left’, go ‘right’. If the answer is ‘right’, go left.)

=====
Reason:

Suppose A always tells the truth, and B always lies.
A would show the correct door, but B would show the incorrect door.

If A is asked, A will tell the truth that B would show the incorrect door.

If B is asked, B will NOT tell the truth that A would show the correct door. Instead, B would tell the lie that A would show the incorrect door.

Therefore, both answers show the incorrect door.
=

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