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Math Help - probability..

  1. #1
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    probability..

    The probability of being left-handed is 0.12. If we sample 25 people at
    random, what is the probability that exactly 2 people are left-handed?


    how do i tackle this one? please
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  2. #2
    MHF Contributor undefined's Avatar
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    Quote Originally Posted by decoy808 View Post
    The probability of being left-handed is 0.12. If we sample 25 people at
    random, what is the probability that exactly 2 people are left-handed?


    how do i tackle this one? please
    Have you learned binomial distribution?

    There are C(25, 2) ways to choose two people out of 25. (This is the same as \binom{25}{2}, just different notation, easier to type in.) For each of these, the probability is (0.12)^2(1-0.12)^{23}.
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  3. #3
    MHF Contributor Unknown008's Avatar
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    You can use a binomial distribution.

    Let X represent the number of left-handed people, where a left-handed person is considered as success.
    Then, X ~ B(25, 0.12)

    P(X = 2) = \binom{25}{2} (0.88)^{25-2}(0.12)^2

    Hope it helps
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