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    Sample Size

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    A previous analysis of paper boxes showed that the standard deviation of their lengths is 13 millimeters. A packer wishes to find the 80% confidence interval for the average length of a box. How many boxes does he need to measure to be accurate within 3 millimeters?

    a.14
    b.19
    c.51
    d.31

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    https://brainmass.com/statistics/sample-size-determination/sample-size-176757

    Solution Preview

    Let the number of boxes that have to be measured be N.

    SD = 13 mm and ...

    Solution Summary

    Problem Solved.

    $2.19

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