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 I don't know. (Posted on 2006-02-16)
ou are a logician in training for the police, and the time has come to take the certification test. The police chief brings you the test one morning, and says, "I must warn you, this is your only chance at the certification test; If you fail, you must keep training for another year before you can take it again."

- Five suspects were interrogated for a bank robbery.

- Each suspect was either a knight, a knave, or a liar.

- Knights always tell the truth.

- Liars always lie.

- Knaves strictly alternate truths and lies with each statement.

- Police have evidence that suggests the perpetrator acted alone.

- Police have evidence that suggests the perpetrator acted alone.

>During the interrogation, two questions were asked (consecutively) of each of the five suspects. Each suspect heard the other suspects' responses, and none of them made a statement between his or her two answers. Here are the two questions and their responses.

"Did you rob the bank?"
A: No.
B: No.
C: No.
D: Yes.
E: Yes.

"Who robbed the bank?"
A: E.
B: A.
C: l don't know.
D: E.
E: A.

The interrogators mentioned that something about their statements didn't seem quite right. The police chief adds, "The only hints I can give you are that C is not a knight and that there is only one correct answer. I'll be back in 24 hours to ask you who robbed the bank."

 No Solution Yet Submitted by Dustin Rating: 3.3333 (6 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
 re: Immediate Knowledge - rebuttle | Comment 3 of 52 |
(In reply to Immediate Knowledge by Cory Taylor)

If C is a liar then by her first statement, she did it. And by her second statement she admits to knowing she did it.

So why can't C be a liar?

If C is a knave then the first statement cannot be a lie because that would make the second a lie. So the first is the truth.  In this case she admits to knowing who did it.

 Posted by Leming on 2006-02-16 16:13:59

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