Chapter 3 [Part I]: A bank manager has developed a new system to reduce the time customers spend waiting to be served by tellers during peak business hours. Typical waiting times during peak business hours under the current system are roughly 9 to 10 minutes. The bank manager hopes that the new system will lower typical waiting times to less than 6 minutes and wishes to evaluate the new system. When the new system is operating consistently over time, the bank manager decides to select a sample of 100 customers that need teller service during peak business hours. Specifically, for each of 100 peak business hours, the first customer that starts waiting for teller service at or after a randomly selected time during the hour will be chosen. [Data Set: WaitTime]

Chapter 3 [Part I]: A bank manager has developed a new system to reduce the time customers spend waiting to be served by tellers during peak business hours. Typical waiting times during peak business hours under the current system are roughly 9 to 10 minutes. The bank manager hopes that the new system will lower typical waiting times to less than 6 minutes and wishes to evaluate the new system. When the new system is operating consistently over time, the bank manager decides to select a sample of 100 customers that need teller service during peak business hours. Specifically, for each of 100 peak business hours, the first customer that starts waiting for teller service at or after a randomly selected time during the hour will be chosen. [Data Set: WaitTime] x= bank customer wait time in minutes Part a. Find the sample mean. Does the sample mean provide some evidence that the mean of the population of all possible customer waiting times during peak business hours is less than six minutes (as is desired by the bank manager)? Explain your answer. Your Comments Part b. Find the sample median. How do the mean and median compare? What does the above histogram tell you about why they compare wait times this way? What do you learn about the normality condition of the "WaitTime" data set? [Hint: This measurement process is approximately normal] 1 Part c. Find both sample variance and sample standard deviation. Part d. Use your results in "Part a" and "Part c" to calculate the first tolerance interval of the Empirical Rule for all possible bank customer waiting times. That tolerance interval is [xs,x+s]. Are 68% of the observations within that interval? How do you interpret your findings here? [Hint: This measurement process is approximately normal.]