Explore BrainMass

Explore BrainMass

    Confidence interval and sample size

    Not what you're looking for? Search our solutions OR ask your own Custom question.

    This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!

    I need to know how to:
    (a) Construct a 95 percent confidence interval for the true mean.
    (b) Why might normality be an issue here?
    (c) What sample size would be needed to obtain an error of ±10 square millimeters with 99 percent confidence?
    (d) If this is not a reasonable requirement, suggest one that is.

    A sample of 20 pages was taken without replacement from the 1,591-page phone directory Ameritech Pages Plus Yellow Pages. On each page, the mean area devoted to display ads was measured (a display ad is a large block of multicolored illustrations, maps, and text). The data (in square millimeters) are shown below:

    0 260 356 403 536 0 268 369 428 536
    268 396 469 536 162 338 403 536 536 130

    © BrainMass Inc. brainmass.com March 4, 2021, 8:20 pm ad1c9bdddf

    Solution Summary

    This solution shows how to construct a confidence interval for a mean, explains why normality is important when sample sizes are small, and finds an appropriate sample size.