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Math Help - Binomial Distributions Question

  1. #1
    Junior Member asemh's Avatar
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    Binomial Distributions Question

    Hi
    Im having trouble doing this question.
    Could someone help me out.

    A factory produces computer chips with a 0.9% defect rate. In a batch of 100 computer chips, what is the probability that

    a) only 1 is defective?
    b) at least 3 are defective?


    I guessed that p = 0.9 and q = 0.1 and n = 100

    For a) I tried (100 Choose 1)*(0.9)^1 * (0.1)^99
    but it turned out wrong..

    The answers in the back of the book were a) 36.8% and b) 6.2%

    How did they get these values?

    Thanks in advance
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  2. #2
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    Hello, asemh!

    A factory produces computer chips with a 0.9% defect rate.
    In a batch of 100 computer chips, what is the probability that

    a) only 1 is defective?

    b) at least 3 are defective?

    I guessed that p = 0.9 and q = 0.1 . {\color{blue}\leftarrow\;\text{Here!}}

    Careful . . .  p \:=\:0.9\% \:=\:0.009

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  3. #3
    Master Of Puppets
    pickslides's Avatar
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    Quote Originally Posted by asemh View Post

    A factory produces computer chips with a 0.9% defect rate. In a
    You are not considering the % sign

    0.9% \implies p = 0.009 . This will give you the answer you require.
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  4. #4
    Junior Member asemh's Avatar
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    oooh!!
    Thanks a lot
    I thought they already converted it into decimals
    Thanks
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