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Math Help - finding sample variance

  1. #1
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    finding sample variance

    having trouble identifying what is what, and alpha is confusing me. thank you

    A random sample of 100 observations was drawn from a normal population. The sample variance was calculated to be 220. Test with alpha = .05 to determine whether we can infer that the population variance differs from 300.
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  2. #2
    MHF Contributor matheagle's Avatar
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    H_o: \sigma^2=300 vs. H_a: \sigma^2\ne 300

    The test statistic is  {(n-1)s^2\over \sigma_o^2}={(99)(220)\over 300}

    NEXT split your alpha in half and put .025 into each tail of a chi-square with 99 dfs.

    You can use the table at http://www.danielsoper.com/statcalc/calc12.aspx
    if you can't find one with 99 dfs.
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