Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Help me in revealing who is the murderer.~ pls

  1. Nov 17, 2009 #1
    Sharky , a leader of the underworld , was killed by one of his own band of four henchmen . Detective Sharp interviewed the men and determined that all were lying except for one. He deduced who killed Shark on the basis of the following statements :

    a) Socko: Lefty Killed Sharky
    b) Fats: Muscles didnt kill Sharky
    c) Lefty: Muscles was shooting craps with Socko when Sharky was knocked off
    d) Muscles: Lefty didnt kill Sharky

    who did kill Sharky?
     
  2. jcsd
  3. Nov 17, 2009 #2

    CRGreathouse

    User Avatar
    Science Advisor
    Homework Helper

    Go through each of the four statements, assuming that that one is correct and the others incorrect. Here's #1:
    By a, Lefty Killed Sharky. By b, Muscles killed Sharky; contradiction.

    So a is lying.
     
  4. Nov 17, 2009 #3
    i do it like this..
    first i negation all of the statements
    second Then i check it 1 by 1 see whether got contradiction a not(like what u had done)
    third if there r a contradiction occurs , i will ignore it and go for the next.
    last i found that it was Muscle who did kill Sharky

    Is it like this?? My logic sense is quite poor..~ hehe
     
  5. Nov 18, 2009 #4

    ssd

    User Avatar

    The question appears to be inconsistent.
    1/ One of (a) or (d) must be true (because one statement is the complement of other)
    2/ Similarly, one of (b) and (c) must be true.
    Therefore, we find two true statement maker {one from (a) or (d) and the other from (b) or (c)}.
    Thus the condition of the question that 'only one is stating the truth' does not hold good.
     
  6. Nov 18, 2009 #5
    I think the question is fine, we have 4 cases to consider.

    CASE 1: Socko is the one telling the truth. Then Lefty killed Sharky is the truth. But if Socko is the only one telling the truth, then the others must be lying. So Fats (who is lying) says that muscles didn't kill Sharky, ...thus Muscles DID kill Sharky. Two different people killed Sharky? Not possible...thus case 1 is ruled out.

    CASE 2: Fats is the one telling the truth. So Socko, Lefty and Muscles are lying.

    So we deduce from Socko's lying statement that...Lefty did not kill Sharky.

    We deduce from Fats' true statement that...Muscles did not kill Sharky.

    We deduce from Muscles lying statement that...Lefty did kill Sharky.

    So Lefty did kill him, but also did not? That's a contradiction. So either case 3 or 4 is true. But you can figure using reasoning that one of them cannot happen...just like I did here.

    CASE 3: 4 u
    CASE 4: 4 u
     
  7. Nov 18, 2009 #6
    Wow..~ But i deduced tat is Muscle who did kill Sharky..T_T''
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Help me in revealing who is the murderer.~ pls
  1. Statistic help pls (Replies: 2)

  2. Please help me (Replies: 1)

  3. Help me with a proof (Replies: 2)

Loading...