A sample of 20 pages was taken without replacement of the 1591 page phone directory "American 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 milimeters) is shown below
0 260 356 403 536 0 268 369 428 536
268 396 469 536 162 338 403 536 536 130
A) construct a 95% 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 + or - 10 square milimeters with 99% confidence?
D) If this is not a reasonable requirement, suggest one that is. (data are from a project by MBA student Daniel Dalach)
Word document attached shows how to construct a confidence interval, identify might normality issues and find the required sample size for data on ad space in a phone directory.