Use the following information to answer questions 7-9: Suppose that shopping times for customers at a local mall are normally distributed with known population standard deviation of 30 minutes. A random sample of 100 shoppers in the local grocery store had a mean time of 60 minutes. Assume 98% confidence interval for the population mean. 8. Calculate the width of the 98% confidence interval estimate. A) 5 B) 0.6 C) 9.84 D) 13.98 E) None of the above is correct. 9. Find the upper confidence limit of the 98% confidence interval. A) 66.99 B) 60.6 C) 69.84 D) 73.98 E) None of the above is correct.
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