Refer to the data for problem 1.
a. Find the average difference between the effectiveness of ad 1 and that of ad 2 (computed as ad 2 minus ad 1).
b.* Find the standard error for this average difference.
c. How many degrees of freedom does this standard error have?
d. Find the 99.9% confidence interval for the population mean difference in effectiveness between ad 1 and ad 2.
e. Are the effectiveness scores of ad 1 and ad 2 very highly significantly different? How do you know?

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TABLE 15.5.1 Analysis of Ad Effectiveness Ad 1 Average Standard deviation Sample size (consumers) 01 Ad 2 63.2 68.1 7.9 113 Ad 3 53.5 9.2 97 105