perplexus.info :: Liars and Knights : Two Bank Robbers

Two Bank Robbers (Posted on 2003-06-27)

In the city of Enigmamia every person is either a knight or a liar. One night, two robbers managed to break into the Enigmamia Central Bank.

Five men were brought to the police station for questioning. It was certain both robbers were present. To narrow the field, each man was individually interrogated about the identities of the robbers. The results were:

Alex: 1. At most one of Bill and Eddy is guilty. 2. Dave is guilty.

Bill: 1. Both Alex and Carl are guilty. 2. Eddy is not guilty.

Carl: 1. At least one of Dave and Eddy is guilty. 2. Bill is not guilty.

Dave: 1. Exactly one of Alex and Bill is guilty. 2. Carl is guilty.

Eddy: 1. Neither Carl nor Dave is guilty. 2. Alex is guilty.

Which two suspects robbed the bank?

Submitted by Brian Smith

Rating: 3.2500 (8 votes)

Solution: (Hide)

If Bill is telling the truth, then Eddy made one true and one false statement. That can't happen since they are either knights or liars. Bill must be a liar. Then, Eddy is one of the robbers. Then, Alex is a knight which means Dave is the other robber.
Summary: Alex and Carl are knights. Bill, Dave and Eddy are liars. Dave and Eddy are the robbers.

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

Subject	Author	Date
answer	K Sengupta	2007-11-14 04:05:38
Solution	Lewis	2003-07-09 08:55:28
i think	amy	2003-07-02 08:25:14
The freaks come out at knight	ben young	2003-07-02 07:45:03
Observations (spoiler)	DJ	2003-06-27 09:14:39
Solution	Jonny Doe	2003-06-27 08:01:53

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