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 meanarea 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
(a) Construct a 95 percent confidence intervalfor 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.
Please see the attachment for the solution to parts a) and c) of this posting.
(b) Why might normality be an issue here? …
This solution provides a step by step response for the calculation of confidence intervals for the mean and sample size. Formulas for the calculation and interpretations of the results are also included. An interactive Excel sheet is included, which allows the user to edit the inputs and obtain the complete results for a new set of data in the future. As well, a Word document file also needs to be opened in order to view parts a) and c) of this solution.