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It seems me true but?

  1. Oct 3, 2009 #1
    it seems me true but prof. said its not..

    You are asked to calculate the probability that a sample of 1000 vaccine vials from a filling line contains no more than two (2) defective closures. From prior data, you know that the particular filling line in question has a defect rate of 0.08%. Given this information, you use the Microsoft Excel BINOMDIST function with number_s =2, trials = 1000, and probability_s = 0.0008. In order to yield the desired probability, you should set the value of cumulative = TRUE and subtract the result of the function from 1.000.

    is that true?

    what is your idea?
  2. jcsd
  3. Oct 3, 2009 #2
    You gave an observed rate of 8 defects per 1000 but no variance. If you can assume a Poisson process then the mean and variance is 8 and the SD=sqrt (8). From this you can estimate the probability of 2 defects per thousand.

    EDIT: I'm confused about your denominator. Is it 1000 or 10000? In either case the above works as long as your denominator doesn't change. You can also use a chi- square estimate where E=8, O=2 and Chi sq=(E-O)^2/E. You can get the probability from Chi Square tables.
    Last edited: Oct 3, 2009
  4. Oct 3, 2009 #3
    SW VandeCarr, thank you very much

    When we set the value of cumulative to TRUE, we already getthe probability of 2 or less
    than 2 (that is no more than 2) defectives. So we need not subtract the answer from 1.
    (The probability answer is 0.9526.)
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