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Balls

Posted By: Ray Kershaw
Date: Thursday, 10 June 2010, at 8:26 p.m.

The answer can be derived by logic. It is not a linguistic trick.

A bag contains 3 red and 2 black balls. A ball is placed in front of each of 3 people, X, Y and Z.

X can see the balls of Y and Z but not of X. Y can see the balls of X and Z but not of Y. Z is blind.

Each person reasons perfectly on the basis of the evidence available. Firstly, X says "I cannot tell what colour is my ball." Secondly, Y says "I cannot tell what colour is my ball." Thirdly, Z says "I know the colour of my ball."

What colour is Z's ball ?

Messages In This Thread

• Balls
  Ray Kershaw -- Thursday, 10 June 2010, at 8:26 p.m.
  • Balls
    ryc -- Thursday, 10 June 2010, at 8:33 p.m.
  • Balls
    Matt Cohn-Geier -- Thursday, 10 June 2010, at 8:36 p.m.
    • Balls
      Ray Kershaw -- Saturday, 12 June 2010, at 9:02 a.m.
      • Balls
        Matt Cohn-Geier -- Saturday, 12 June 2010, at 11:20 a.m.
        • Balls
          Tom Keith -- Saturday, 12 June 2010, at 1:17 p.m.
          • Balls
            Matt Cohn-Geier -- Saturday, 12 June 2010, at 2:50 p.m.
            • Balls
              Tom Keith -- Saturday, 12 June 2010, at 3:54 p.m.
              • Balls
                Casper van der Tak -- Saturday, 12 June 2010, at 4:17 p.m.
              • Balls
                Bob Koca -- Saturday, 12 June 2010, at 4:25 p.m.
  • Balls RO Warning!!
    Casper van der Tak -- Thursday, 10 June 2010, at 8:38 p.m.
  • Balls
    Alejandro -- Thursday, 10 June 2010, at 9:34 p.m.
  • Balls
    Bob Koca -- Friday, 11 June 2010, at 11:56 p.m.
  • Balls * Spoiler
    Joe Russell -- Saturday, 12 June 2010, at 12:18 a.m.
  • Balls
    garyo -- Saturday, 12 June 2010, at 4:47 p.m.