Question 1.1. Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service level provided to walk-in customers. Accordingly, his staff recorded the waiting times for 45 randomly selected walk-in customers, and calculated that their mean waiting time was 15 minutes. If Brian concludes that the average waiting time for all walk-in customers is 15 minutes, he is using a/an ________. (Points : 3)
range estimate
statistical parameter
interval estimate
point estimate
exact estimate
Question 2.2. Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service level provided to walk-in customers. Accordingly, his staff recorded the waiting times for 64 randomly selected walk-in customers and determined that their mean waiting time was 14 minutes. Assume that the population standard deviation is 4 minutes. The 90% confidence interval for the population mean of waiting times is ________. (Points : 3)
14.27 to 15.73
14.18 to 15.82
9.88 to 20.12
13.18 to 14.82
18.12 to 19.87
Question 3.3. The normal distribution is used to test about a population mean for large samples if the population standard deviation is known. "Large" is usually defined as _______. (Points : 3)
at least 10
at least 5% of the population size