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Math Help - Basic Standard Deviation Calculation

  1. #1
    Super Member craig's Avatar
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    Basic Standard Deviation Calculation

    Hi, it's been a while since I've attempted any statistics a just wondering if you could check that I'm using the right method to calculate the standard deviation.

    We're given than the mean, \bar{x} = 8.35, \Sigma x = 334 and \Sigma x^2 = 3002 with a sample size of 40.

    I used the formula \sigma =\sqrt{\Sigma (x^2) - \bar{x}^2}.

    Is this the correct formula to use or have I gone wrong somewhere?

    Thanks
    Last edited by craig; November 10th 2009 at 10:30 AM. Reason: Wrong formula entered
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  2. #2
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    it's \sigma =\sqrt{\frac{\sum x^2}{n} - \bar{x}^2}

    where n=40
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    Super Member craig's Avatar
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