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Math Help - normal approximation

  1. #1
    Yan
    Yan is offline
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    normal approximation

    If 23 percent of all patients with high blood pressure have had side effects from certain kind of medicine, use the normal approximation to find the probability that among 120 patients with high blood pressure treated with this medicine more than 32 will have bad side effects
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  2. #2
    MHF Contributor matheagle's Avatar
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    Thats a normal approximation to a Binomial with n=120 and p=.23
    The mean is np and the VARIANCE is npq.
    You want  P\{Y>32\}
    where Y is Bin(120,.23)
    Let X be our normal with the same mean and variance.
    YOU should include the correction factor.
    So  P\{Y>32\}\approx P\{X>32.5\}
    NOW center this X, by subtracting the mean (120)(.23)
    and dividing by it's st dev  \sqrt{npq}
    The answer will be
    P\Biggl\{Z>{32.5-(120)(.23)\over \sqrt{120(.23)(.77)}} \Biggr\}
    How's that 4 typing in TeX?
    I had no idea of how you were doing it here.
    NO one has helped me with my question.
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