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    Confidence Interval for Mean

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    Average electric usage was studied. A previously known population standard deviation was 450 KWH. A sample of 81 houses was studied and found to have a mean of 1858 KWH.

    Find the 95% confidence interval for the true mean.

    © BrainMass Inc. brainmass.com June 3, 2020, 10:51 pm ad1c9bdddf
    https://brainmass.com/statistics/confidence-interval/confidence-interval-mean-253173

    Solution Preview

    The formula for a proportion confidence interval is:

    mean ± z * standard deviation / square ...

    Solution Summary

    The 95% confidence interval for the true mean is determined.

    $2.19

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