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Math Help - probability with percent given.

  1. #1
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    probability with percent given.

    a manufacturing plant makes dishes that are carefully inspected for the right dimensions, quality, and product trends. after studies the factory does produce 15% defectives. most of these pieces are found through inspection and redone or thrown away. Suppose two pieces are randomly selected for inspection.

    what is the probablity that both pieces are defect free?

    what is the probablity that neither piece is defect free?

    also, if at least one of the pieces has a flaw . what is the probability that both are defective?

    thanks for any help with this problem.
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  2. #2
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    You should consider the binomial theorem

    Where n is number of trials, p is the probabilty of success and k is the required amount.

     P(X=k) = \binom{n}{k}p^k(1-p)^{n-k}

    In your case n = 2 and p = 1-0.15 = 0.85

    Quote Originally Posted by rcmango View Post
    what is the probablity that both pieces are defect free?

    Choose k = 2


    Quote Originally Posted by rcmango View Post

    what is the probablity that neither piece is defect free?

    Choose k = 0

    Quote Originally Posted by rcmango View Post
    also, if at least one of the pieces has a flaw . what is the probability that both are defective?
    make p = 0.15 and find k=1,2 i.e P(k=1)+P(k=2)
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  3. #3
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    thankyou btw.
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