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Math Help - How to find what % of the data lies within one standard deviation of the mean

  1. #1
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    How to find what % of the data lies within one standard deviation of the mean

    DATA SET:

    5.3
    7.2
    5.5
    6.5
    5.7
    4.7
    7.5
    7.5
    7.1
    5.4
    5.4
    4.4
    5.7
    6.3
    4.2
    7.1

    My work:

    Mean: 5.969
    St. dev: 1.090

    5.969 + (1.090) = 4.879
    5.969 - (1.090) = 7.059

    Range: 4.879-7.059

    8 of 16 values are in that range

    answer 50%

    WHERE DID I GO WRNOG?
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by -DQ- View Post
    answer 50%

    WHERE DID I GO WRNOG?
    Why do you think you have gone wrong?

    CB
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  3. #3
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    Because the answer in the book is different.
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  4. #4
    Grand Panjandrum
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    Quote Originally Posted by -DQ- View Post
    Because the answer in the book is different.
    There are two possibilities:

    1. You should have used 1/n weighting in the calculation of the SD rather than 1/(n-1) (they give the same final answer when I do the calculations either way)

    2. The book is wrong (what does it think the answer is?)

    CB
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