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Paired t test: No. of ad pages

I am having problems with Excel. I just don't understand how to make it do what I need it to do.

This is what I have in Excel 2010:
Magazine 2008 2009
Details 72.31 48.42
Esquire 66.69 42.79
Field & Stream 48.65 42.82
Flex 219.61 231.58
GQ 99.21 60.35
Maxim 68.5 41.82
Men's Fitness 99.43 67.63
Men's Health 90.88 74.45
Men's Journal 183.1 88.34
Mucscle & Fitness 169.63 198.93
Outdoor Life 41.39 30.16
Outside 126.97 103.58

In tough economic times, the business staff at magazines are challenged to sell advertising space in their publications. Thus, one indicator of a weak economy is the decline in the number of "ad pages" that magazines have sold. The file contains the number of ad pages found in the May 2008 and May 2009 issues of 12 men's magazines. (Data extracted from W. Levith, "Magazine Monitor," Mediaweek, April 20, 2009, p. 53.)
a) At the 0.05 level of significance, is there evidence that the mean number of ad pages was higher in May 2008 than in May 2009?
b) What assumption is necessary about the population distribution in order to perform this test?
c) Use a graphical method to evaluate the validity of the assumption in (b).
d) Construct and interpret a 95% confidence interval estimate of the difference in the mean number of ad pages in men's magazines between May 2008 and May 2009.

Please see the attachment


Solution Summary

The solution provides step by step method for the calculation of testing of hypothesis. Formula for the calculation and interpretations of the results are also included. Interactive excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.