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Probability of two teams

  1. Jan 30, 2009 #1
    1. The problem statement, all variables and given/known data

    suppose that 35 people are divided in a random manner into two teams in such a way that one team contains 10 people and the other team contains 25 people. What is the probability that two particular people A and B will be on the same team.

    2. Relevant equations

    I don't have the answer on this problem , I am confused. Please help.

    3. The attempt at a solution

    35 people team C contains 10 people, so the chance to be in this team is 2/7
    team D contains 25 people, so the chance is 5/7
    when person A is divided in team C , then there is a chance for person B, to be also in this team, namely 9/34(1 person is already divided)
    when person B is divided in team D, then there is a chance for person B, to be also in this team, namely 24/34
    so there are 2 cases
    case 1 has a chance of 2/7*9/34=18/238
    case 2 has a chance of 5/7*24/34=120/238
    together this is 138/238=69/119 (=0.58) that they are in the same team (the chance is always bigger than 50%)
  2. jcsd
  3. Jan 30, 2009 #2
    Re: probability

    I get the same answer.
  4. Jan 30, 2009 #3
    Re: probability

    Then it is okay. Thanks.
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