Results 1 to 5 of 5

Math Help - random prob

  1. #1
    Junior Member
    Joined
    Jul 2008
    Posts
    53

    random prob

    Consider two people being randomly selected. What is the probability that two people were born on Friday?how can i solve this?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Jan 2008
    From
    Montreal
    Posts
    311
    Awards
    1
    The probability that person 1 is born on a Friday is:

    P(X_1=F) = \frac{1}{7}

    and the probability that person 2 is born on a Friday is:

    P(X_2=F) = \frac{1}{7}

    so both would be P(X_2=F) \times P(X_1=F) = \frac{1}{7} \times \frac{1}{7} = \frac{1}{49}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Jul 2008
    Posts
    53
    What is the probability that two people have a birthday in August?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Senior Member
    Joined
    Jan 2008
    From
    Montreal
    Posts
    311
    Awards
    1
    P(X_1= Aug) = \frac{1}{12}

    P(X_2= Aug) = \frac{1}{12}

    same argument as before

    P(X_1= Aug) \times P(X_2= Aug) = \frac{1}{12} \times \frac{1}{12} = \frac{1}{144}
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by lllll View Post
    P(X_1= Aug) = \frac{1}{12}

    P(X_2= Aug) = \frac{1}{12}

    same argument as before

    P(X_1= Aug) \times P(X_2= Aug) = \frac{1}{12} \times \frac{1}{12} = \frac{1}{144}
    Assuming the one is equally likely to be born on any day in the year the ptobability that one is born in August is 31/363.25

    RonL
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 2
    Last Post: April 12th 2011, 10:13 AM
  2. Probability and random random varible question
    Posted in the Advanced Statistics Forum
    Replies: 1
    Last Post: May 15th 2010, 08:53 PM
  3. Replies: 3
    Last Post: January 13th 2010, 10:44 AM
  4. Replies: 6
    Last Post: November 14th 2009, 11:23 PM
  5. Random Variables and Prob Distributions
    Posted in the Statistics Forum
    Replies: 9
    Last Post: November 12th 2009, 06:49 AM

Search Tags


/mathhelpforum @mathhelpforum