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Homework Help: Binomial distribution smallest value

  1. Jan 5, 2005 #1
    could someone please shed some light upon the following dilemma:

    Given that D~B(12,0.7), calculate the smallest value of d such that
    P(D>d) <0.90.

    much obliged
  2. jcsd
  3. Jan 5, 2005 #2
    I am going to replace the D with an X and the d with an x and the B with a Bin.

    From this you know that n=12, p=0.7, q=0.3 and x=d.
    n is the number of trials, p is the probability of the event n happening and q is 1 - p.

    So X~Bin(12,0.7) = [tex]^nC_r p^r q^n^-^r = ^{12}C_0[/tex] [tex]0.7^0[/tex] [tex]0.3^{12} = 1\times1\times0.0053 = 0.0053[/tex]

    All you then need to do this for the next few until you get an answer which answers your question.

    The Bob (2004 ©)

    EDIT: I think this post needs a little more information but I have not the time now. Sorry.
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