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Posers and Puzzles

Posers and Puzzles

  1. 16 Jun '04 14:16
    You have four addressed letters and four addressed envelopes. If you close your eyes and randomly insert letters into envelopes, what is the probability that exactly three letters will be in the right envelopes?

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  2. Donation bbarr
    Chief Justice
    16 Jun '04 14:27 / 1 edit
    Originally posted by THUDandBLUNDER
    You have four addressed letters and four addressed envelopes. If you close your eyes and randomly insert letters into envelopes, what is the probability that exactly three letters will be in the right envelopes?

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    1/4 X 1/3 X 1/2 = 1/24

  3. 16 Jun '04 14:31
    Originally posted by bbarr
    1/4 X 1/3 X 1/2 = 1/24
    Nope.
  4. Donation bbarr
    Chief Justice
    16 Jun '04 14:59
    Originally posted by THUDandBLUNDER
    Nope.
    Tricky. The probability is 0. If three are correct then the fourth must be also. Of course, the probability I gave above was for randomly placing all four envelopes correctly.
  5. Standard member Coletti
    W.P. Extraordinaire
    17 Jun '04 01:32
    Originally posted by bbarr
    Tricky. The probability is 0. If three are correct then the fourth must be also. Of course, the probability I gave above was for randomly placing all four envelopes correctly.
    Cool! I think you're right bbarr, the answer is zero for the reason you stated. And I was going to add that THUDandBLUNDER should have stated that only one letter should go into any one envelope, but that would given to big a clue to the solution and made it too easy.
  6. 17 Jun '04 17:10
    Im pretty sure it's not zero, because it is possible for it to happen. I can't remember the equation off hand, but it's not quite 4! - I'll consult my communications book -
  7. Standard member Otis
    Lucky Patzer
    18 Jun '04 06:51
    what if i stuffed 3 letters in the correct envelopes and then stuffed the extra letter with another letter leaving an envelop empty then there could be 3 correct and 1 false
  8. 18 Jun '04 08:19 / 1 edit
    Originally posted by Otis
    what if i stuffed 3 letters in the correct envelopes and then stuffed the extra letter with another letter leaving an envelop empty then there could be 3 correct and 1 false
    Perhaps I should have made it clear that one and only one letter goes into each envelope, in which case the right answer is zero.

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  9. Standard member Otis
    Lucky Patzer
    18 Jun '04 08:22
    0 because you have no hands duh
  10. 19 Jun '04 08:23
    well if you only stuff 3 of the envelopes with letters, then what is the probability?
  11. 19 Jun '04 11:18 / 1 edit
    Originally posted by Awry
    well if you only stuff 3 of the envelopes with letters, then what is the probability?
    Probability = (1/4)(1/3)(1/2) = 1/24

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