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Math Help - z value

  1. #1
    lynne smith
    Guest

    statistics

    Here is my problem:

    Recently you ran a large study over 200,000 data points and came up with a mean,median, and standard deviation.
    mean= 345
    median= 340
    standard deviation =45
    would you consider the data to br normally distributed?

    3(345-340) /45
    3(5) /45=
    15/45=
    .333
    because the data falls between -3 and positive 0.3 the data is normal.

    Please let me know if i need to make any corrections.Thank you, Lynne
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  2. #2
    hpe
    hpe is offline
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    Joined
    Apr 2005
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    Quote Originally Posted by lynne smith
    Here is my problem:
    Recently you ran a large study over 200,000 data points and came up with a mean,median, and standard deviation.
    mean= 345
    median= 340
    standard deviation =45
    would you consider the data to br normally distributed?
    If the data were normal, N(345,45), the sampling distribution of the median with 200,000 data points would be approximately normal with mean 345 and st. dev. 1.25 \cdot 45/\sqrt{200,000} \approx 0.125.So the actual sample median of 340 would have a z-score of -40, extremely unlikely. The data are definitely not normally distributed.
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