perplexus.info :: Liars and Knights : Only One Question

Only One Question (Posted on 2005-02-16)

The following two facts are known about Adam, Bert, and Carl:

1) Of Adam, Bert, and Carl, there is one knight, one knave, and one liar.
2) Adam said once, "Bert said that Carl isn't a knight."

Can you ask one yes/no question to one person and figure out who is who? If not, how many questions must you ask?

Submitted by Dustin

Rating: 4.0000 (8 votes)

Solution: (Hide)

You must ask at least three questions.

Charlie posted his solution, which was worded better than mine. You can find it here: http://perplexus.info/show.php?pid=2853&cid=21062

Comments: ( You must be logged in to post comments.)

Subject	Author	Date
Sol	Andre	2010-06-01 18:31:57
Answer	K Sengupta	2008-11-15 06:49:22
re(3): Two Questions	lance	2006-03-23 08:02:09
0 questions (but you wont know for sure)	Sage	2006-02-02 18:33:52
Yep, it's wrong	Amber	2005-05-20 03:11:58
Two Questions! Must be wrong somewhere.	Amber	2005-05-19 06:13:28
A Knavish definition	Penny	2005-02-27 09:05:19
(-) * (+) = -	turki	2005-02-26 18:49:05
probly not right	angrypie111	2005-02-23 00:19:17
Solution	Penny	2005-02-18 22:43:42
re: it can be done in one question.	Penny	2005-02-18 20:45:52
other ways	joshua imperato	2005-02-18 19:03:01
it can be done in one question.	joshua imperato	2005-02-18 18:49:49
re(4): Two Questions	Liam	2005-02-18 16:29:52
re(3): Two Questions	Ben Gornall	2005-02-18 09:08:07
re(2): Two Questions	Liam	2005-02-17 13:54:45
I'm feeling lazy, but	Ben Gornall	2005-02-17 05:29:19
Three possibilities	Leming	2005-02-17 02:00:18
2 question solution	Robert Woods	2005-02-17 00:37:57
re: Two Questions	John	2005-02-17 00:03:28
Two Questions	Liam	2005-02-16 20:52:02
re: part one	Charlie	2005-02-16 20:20:46
part one	Charlie	2005-02-16 19:27:11

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