The Canadian Retail Council conducted a survey of advertising budgets for various types of businesses in Canada. The survey reported that the average advertising budget for a random sample of furniture stores was 7.1 percent of sales (source: tekvantage.com). Assume that the population standard deviation is 2.2 percent. Show the 95% confidence interval estimate of the average for all Canadian furniture stores if the sample size was
a. 40.
b. 100.
c. If the 95% interval was reported as 7.0 to 7.2, what was the sample size used in the study?