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Math Help - Confidence Inervals

  1. #1
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    Confidence Inervals

    The snout vent lengths (in centimeters) in 20 newly born garter snakes selected at random from several litters are given below. Compute the 95% and the 99% confidence intervals for the population mean.

    6.5, 6.2, 4.9, 5.1, 4.3, 5.8, 5.0, 5.4, 4.6, 5.4, 4.7, 4.8, 6.0, 5.2, 3.4, 3.8, 4.7, 4.8, 3.9, and 6.1

    So far what I did was get the mean and standard deviation from the data given above.

    Mean = ( Σ xi ) / n = 100.6 / 20 = 5.03

    Standard deviation = sqrt[ (1/n) * Σ (xi - mean)^2 ] = sqrt[ (1/20) * 13.022 ] = 0.807

    I'm not sure if I am solving this correctly or not. Please help?
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  2. #2
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    Re: Confidence Inervals

    It looks like you are fine so far.

    Just convert 95% and 99% into the number of standard deviations about the mean and apply that to the mean.
    Last edited by romsek; March 30th 2014 at 05:56 PM.
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