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Math Help - [SOLVED] Finding Standard Deviation

  1. #1
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    [SOLVED] Finding Standard Deviation

    Q: A company manufactures batteries in batches of 21 and there is a 3% rate of defects. Find the standard deviation for the number of defects per batch.
    A: 0.782

    I know how to find standard deviation when given a list of data but how can I find it when just given the information above?
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  2. #2
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     \sigma = \sqrt{np(1-p)}

    in your case n = 21 and p = \frac{3}{100}

    give it a shoot!
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  3. #3
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    ^ Thank you for the help it worked. =)
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