Results 1 to 2 of 2
Like Tree1Thanks
  • 1 Post By HallsofIvy

Math Help - Probability of an independent event

  1. #1
    Newbie
    Joined
    Feb 2013
    From
    New York City
    Posts
    10

    Probability of an independent event

    Each day, Mr.Samms randomly chooses 2 students from his class to serve as helpers. If there are 15 boys and 10 girls in the class, what is the probability that Mr.Samms will choose 2 girls to be helpers?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Apr 2005
    Posts
    14,973
    Thanks
    1121

    Re: Probability of an independent event

    First, this is "sampling without replacement" (he can't choose the same person twice) so the events are NOT "independent". The probability he chooses two girls is equal to the probability the first student chosen is a girl multiplied by the probability the second student is a girl given that the first student chosen was a girl.

    Initially, there are 25 students, 10 of whom are girls. Assuming all students are equally likely to be chosen, what is the probability that the first student chosen? Now how many students are left to choose from? How many of them are girls?
    Last edited by HallsofIvy; March 7th 2013 at 06:50 PM.
    Thanks from chels2000
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: July 16th 2012, 10:49 AM
  2. Show event is completly independent of another event
    Posted in the Advanced Statistics Forum
    Replies: 6
    Last Post: December 18th 2009, 01:27 PM
  3. Probability of Independent event
    Posted in the Statistics Forum
    Replies: 9
    Last Post: December 11th 2009, 02:17 PM
  4. Probability of an event
    Posted in the Statistics Forum
    Replies: 1
    Last Post: May 1st 2009, 10:06 PM
  5. independent or dependent event
    Posted in the Algebra Forum
    Replies: 1
    Last Post: June 5th 2007, 04:12 AM

Search Tags


/mathhelpforum @mathhelpforum