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Math Help - One more question

  1. #1
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    One more question

    10% of items produced by a machine are defective. Out of 15 items chosen at random,

    a. what is the probability that exactly 3 items are defective?

    b. probability less than 3 items are defective?

    c. probability that exactly 11 items will be non-defective?



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  2. #2
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    Quote Originally Posted by hpquintero View Post
    10% of items produced by a machine are defective. Out of 15 items chosen at random,

    a. What is the probability that exactly 3 items are defective?
    0.1^{3} * 0.9^{12}

    b. Probability less than 3 items are defective?
    0.1^{2} * 0.9^{13}+0.1 * 0.9^{14}+0.9^{15}

    c. Probability that exactly 11 items will be non-defective?

    0.1^{11} * 0.9^{4}
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  3. #3
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    Quote Originally Posted by RhysGM View Post
    0.1^{3} * 0.9^{12}


    0.1^{2} * 0.9^{13}+0.1 * 0.9^{14}+0.9^{15}




    0.1^{11} * 0.9^{4}
    Sorry but all these answers are wrong.

    Let X be the random variable number of defective items.

    X ~ Binomial(n = 15, p = 0.1)

    (a) Calculate \Pr(X = 3).

    (b) Calculate \Pr(X \leq 2).

    (c) Calculate \Pr(X = 4).
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