Results 1 to 4 of 4

Math Help - Random Number Generator

  1. #1
    Member
    Joined
    Sep 2007
    Posts
    75

    Random Number Generator

    If a random number generator generated random numbers between 1 and 5 (including both) until it generated a 5, what is the chance that no number before then will have been generated more than once?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Apr 2008
    Posts
    1,092
    It should be clear (by the pigeonhole principle) that the five must be generated no later than fifth in the sequence if each other number is to have been generated only once.

    Then either the five is generated first, second, third, fourth, or fifth.

    P(1) = 1/5

    P(2) = (4/5)x(1/5)

    P(3) = (4/5)x(3/5)x(1/5)

    P(4) = (4/5)x(3/5)x(2/5)x(1/5)

    P(5) = (4/5)x(3/5)x(2/5)x(1/5)x(1/5)

    Just add up the probabilities from there.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Sep 2007
    Posts
    75
    Nice one. I think this is correct.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by Obsidantion View Post
    If a random number generator generated random numbers between 1 and 5 (including both) until it generated a 5, what is the chance that no number before then will have been generated more than once?
    This looks vaguely familiar, it may have been asked elsewhere on MHF recently.

    CB
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. R Language Random Number Generator
    Posted in the Advanced Statistics Forum
    Replies: 16
    Last Post: February 6th 2011, 05:32 AM
  2. Replies: 2
    Last Post: July 29th 2010, 06:48 AM
  3. Random Sequence Generator
    Posted in the Math Forum
    Replies: 0
    Last Post: July 3rd 2010, 09:38 AM
  4. Minimum number of generator assemblies
    Posted in the Advanced Algebra Forum
    Replies: 2
    Last Post: September 9th 2009, 01:41 AM

Search Tags


/mathhelpforum @mathhelpforum