Problem of the Day
A new programming or logic puzzle every Mon-Fri

Who Killed Billy?

This is a fun one that has been floating around the internet. Enjoy your weekend everyone!

Billy "The Knife", the infamous tough guy, was found murdered one night in an alleyway behind the nightclub he used to frequently visit. The police brought in three suspects on the next morning. One of the officers interrogated the three men and noted down the following statements.

Alex:

  1. I did not kill Billy.
  2. Jimmy is not my friend.
  3. I knew Billy.

Jimmy:

  1. I did not kill Billy.
  2. Alex and Dexter are friends of mine.
  3. Alex did not kill Billy.

Dexter:

  1. I did not kill Billy.
  2. Alex lied when he said that Jimmy was not his friend.
  3. I do not know who killed Billy.

Only one of the three is guilty, and only one of each man statements is false. Who killed Billy The Knife?

Permalink: http://problemotd.com/problem/who-killed-billy/

Comments:

  • Anonymous - 9 years, 8 months ago

    Ans : Dexter

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  • David - 9 years, 8 months ago

    Out of all the suspects, he is the easiest to eliminate. If he killed Billy, he also knows who the killer is. That makes 2 lies, which breaks the rules.

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  • k4rtik - 9 years, 8 months ago

    Jimmy is the killer.

    False statements from each:
    - Alex - 2. Jimmy is not his friend.
    - Jimmy - 1. He did not kill Billy.
    - Dexter - 3. He doesn't know who killed Billy.

    reply permalink

  • Jack le - 9 years, 8 months ago

    Alex couldn't have killed Billy because then his first statement would be false and the other 2 would be true, which would make jimmy's second and third statement false which is not the case. Dexter couldn't have killed Billy because then his first and third statements will be false which is also illegal. Therefore, Jimmy killed Billy.

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