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Knowing the Natives (Posted on 2003-08-16) Difficulty: 2 of 5
I met two natives on an island - Benny and Lenny. They are either a knight, a liar or a knave. Knights always tell the truth, liars always lie and knaves alternate between truth and lie. They tell me this:

Benny : We are both of the same type.
Lenny : I am a knave.
Benny : Lenny is a liar.

A knight then tells me what Lenny is. From this I was able to work out what they were.

What are Benny and Lenny?

  Submitted by Lewis    
Rating: 3.8000 (5 votes)
Solution: (Hide)
Lenny is a liar; Benny is a knave.

Their statements were:

Benny : We are both of the same type.
Lenny : I am a knave.
Benny : Lenny is a liar.

So if I was told Lenny was a knight you get a contradiction, so that's not right.

If I was told than Lenny is a knave then Benny could still be a liar or a knave, so that isn't right either, because the problem states that I was able to determine what Benny is from knowing Lenny's type.

If I was told that Lenny was a liar, then Benny's second statement is true. This means his first statements is false, as he cannot be a liar, so he can only be a knave.

While the statements alone allow for more than one possibility for their types, being told that Lenny is a liar is the only way that I am able to determine what Benny is.

So the answer is : I was told that Lenny was a liar and I worked out that Benny was a knave.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
SolAndre2010-06-02 18:48:21
SolutionPuzzle SolutionK Sengupta2008-05-14 16:03:00
AnswerK Sengupta2008-05-12 16:11:54
guess!Shelly2003-08-22 09:44:48
SolutionSolutionTheGreatOne2003-08-18 11:27:14
You Got Me!rose albrecht2003-08-18 01:50:35
solutionlesa2003-08-16 21:46:08
SolutionFull SolutionDJ2003-08-16 20:06:19
re(3): ummmLewis2003-08-16 13:03:44
re(2): ummmMr. Spock2003-08-16 11:42:25
Solutionre: ummmGamer2003-08-16 11:34:35
Couple of KnavesMr. Spock2003-08-16 11:30:54
HmMmOmphie2003-08-16 10:48:10
Some ThoughtsummmGert2003-08-16 10:32:41
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