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Posers and Puzzles

Posers and Puzzles

  1. 16 Jun '04 14:15
    Each member of a set of four cards has a letter of the alphabet on one side and a number on the other. The four cards are placed on a table so that we can see the sequence D, F, 3, 2. You want to find out if every card with a ‘D’ on one side has a ‘3’ on the other side. You are allowed to turn over two cards. Which two cards would you turn over, and why?

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  2. Donation bbarr
    Chief Justice
    16 Jun '04 14:26
    Originally posted by THUDandBLUNDER
    Each member of a set of four cards has a letter of the alphabet on one side and a number on the other. The four cards are placed on a table so that we can see the sequence D, F, 3, 2. You want to find out if every card with a ‘D’ on one side has a ‘3’ on the other side. You are allowed to turn over two cards. Which two cards would you turn over, and why?

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    Turn over the D and the 2. If the card showing D has something other than 3 on its opposite face, you'll have disproved the rule. If the card showing 2 has the letter D on its opposite face, you'll have disproved the rule.
  3. 16 Jun '04 14:26
    D and 2. the D to see if there is a 3 on the other side, and the 2 to see if there is a D.
    You don't have to turn the F, because if there is a 3, it doesn't matter; same for the 2. You want to check D=>3, and not F=>? or ?=>2.
  4. 16 Jun '04 14:32
    Both correct!

    Deja vu?
  5. 16 Jun '04 14:33
    Originally posted by THUDandBLUNDER
    Both correct!

    Deja vu?
    Just easy