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Probability Problem

Posted By: Gregg Cattanach
Date: Thursday, 27 August 2009, at 5:37 p.m.

In Response To: Probability Problem (Neil Robins)

I think Neil has stumbled on the issue. If she has the ace of spades, it seems implied that she won't announce "I have an ace", but rather is forced to announce "I have the ace of spades". That would change the probability in the first case to 6/15 instead of 6/22.

If announcing "I have an ace" is equivalent to "I have an ace and neither of my cards are the ace of spades", then 6/15 is the right answer, (and 3/7 is still correct for "I have the ace of spades").

If she is allowed to simply announce "I have an ace" when she actually HAS the ace of spades, the problem is malformed and needs to be more specific.

I'm assuming she looks at both of her cards before announcing.

Messages In This Thread

• Probability Problem
  poseidon -- Thursday, 27 August 2009, at 1:26 p.m.
  • Probability Problem
    misja -- Thursday, 27 August 2009, at 1:42 p.m.
    • Probability Problem
      Stick -- Thursday, 27 August 2009, at 3:31 p.m.
    • Probability Problem
      Petter Bengtsson -- Thursday, 27 August 2009, at 3:46 p.m.
  • Probability Problem
    Gregg Cattanach -- Thursday, 27 August 2009, at 3:49 p.m.
    • Probability Problem
      Bob Koca -- Thursday, 27 August 2009, at 4:19 p.m.
    • Probability Problem
      Chuck Bower -- Thursday, 27 August 2009, at 4:46 p.m.
    • Probability Problem
      Jason Lee -- Thursday, 27 August 2009, at 7:54 p.m.
  • Probability Problem
    Neil Robins -- Thursday, 27 August 2009, at 4:14 p.m.
    • Probability Problem
      Gregg Cattanach -- Thursday, 27 August 2009, at 5:37 p.m.
      • Probability Problem
        Bob Koca -- Thursday, 27 August 2009, at 5:56 p.m.
        • Probability Problem
          Gregg Cattanach -- Thursday, 27 August 2009, at 6:07 p.m.
          • Probability Problem
            Bob Koca -- Thursday, 27 August 2009, at 7:42 p.m.
            • Probability Problem
              Gregg Cattanach -- Thursday, 27 August 2009, at 8:09 p.m.
              • Probability Problem
                joe freedman -- Thursday, 27 August 2009, at 8:26 p.m.
                • Probability Problem
                  poseidon -- Thursday, 27 August 2009, at 8:37 p.m.
                • Probability Problem
                  Jason Lee -- Thursday, 27 August 2009, at 8:47 p.m.
              • Probability Problem
                Gregg Cattanach -- Friday, 28 August 2009, at 1:58 a.m.
                • Probability Problem
                  Paul Vianna -- Friday, 28 August 2009, at 2:11 a.m.
                  • Probability Problem
                    Chuck Bower -- Friday, 28 August 2009, at 4:06 p.m.
            • monte hall called this
              garyo -- Saturday, 29 August 2009, at 7:51 a.m.
  • Probability Problem
    Chuck Bower -- Thursday, 27 August 2009, at 5:16 p.m.
  • Probability Problem
    Timothy Chow -- Thursday, 27 August 2009, at 6:03 p.m.
    • Probability Problem
      Bob Koca -- Thursday, 27 August 2009, at 6:06 p.m.
      • Probability Problem
        poseidon -- Thursday, 27 August 2009, at 6:18 p.m.
  • Probability Problem
    joe freedman -- Thursday, 27 August 2009, at 6:35 p.m.
    • Probability Problem
      joe freedman -- Thursday, 27 August 2009, at 6:39 p.m.
  • Probability Problem
    Jason Lee -- Thursday, 27 August 2009, at 7:57 p.m.
  • Probability Problem
    Bob Koca -- Friday, 28 August 2009, at 2:13 a.m.
    • Probability Problem
      poseidon -- Friday, 28 August 2009, at 10:29 a.m.