Posers and Puzzles

Posers and Puzzles

  1. Joined
    29 Feb '04
    Moves
    22
    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. Donationbbarr
    Chief Justice
    Center of Contention
    Joined
    14 Jun '02
    Moves
    17381
    16 Jun '04 14:271 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. Joined
    29 Feb '04
    Moves
    22
    16 Jun '04 14:31
    Originally posted by bbarr
    1/4 X 1/3 X 1/2 = 1/24
    Nope.
  4. Donationbbarr
    Chief Justice
    Center of Contention
    Joined
    14 Jun '02
    Moves
    17381
    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 memberColetti
    W.P. Extraordinaire
    State of Franklin
    Joined
    13 Aug '03
    Moves
    21735
    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. Joined
    10 Jun '04
    Moves
    2145
    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 memberOtis
    Lucky Patzer
    Ohio University
    Joined
    23 Oct '03
    Moves
    9879
    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. Joined
    29 Feb '04
    Moves
    22
    18 Jun '04 08:191 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 memberOtis
    Lucky Patzer
    Ohio University
    Joined
    23 Oct '03
    Moves
    9879
    18 Jun '04 08:22
    0 because you have no hands duh
  10. Joined
    19 Jun '04
    Moves
    119
    19 Jun '04 08:23
    well if you only stuff 3 of the envelopes with letters, then what is the probability?
  11. Joined
    29 Feb '04
    Moves
    22
    19 Jun '04 11:181 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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