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Math Help - Statistics basic question

  1. #1
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    Statistics basic question

    Hello people I have this problem to solve.

    The probability that a patient recovers from a rare blood disease is 0.6. If 18 people are known to have contracted this disease, what is the probability that:

    (i) at least 15 survive?
    p=0.6

    15/18*0.6=0.5, 50%

    (ii) from 5 to 10 survive?


    (iii) Exactly 12 survive?

    (I have attempted the first part not sure if it is correct. Really appreciate replys in regads to the answer).
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  2. #2
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    Use the binomial theorem for these problems,
     P(X=k) = \binom{n}{k}p^k(1-p)^{n-k}

    In your case n = 18 & p= 0.6

    a) P(X=15)+P(X=16)+P(X=17)+P(X=18)

    b) P(X=5)+P(X=6)+P(X=7)+P(X=8)+P(X=9)+P(X=10)

    c) P(X=12)

    I don't think your attempt for part a) is very robust.
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  3. #3
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    Thanks for your reply pickslides. Yes now I know where to use that x value cheers.
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