Time Warner has urbanized a new system to decrease the time customers spend waiting to be served by technical reps during peak business hours. Typical waiting times during peak business hours under the current system are roughly 9 to 10 minutes. The manager hopes that the new system will lower typical waiting times to less than six minutes and wishes to evaluate the new system. When the new system is operating consistently over time, the manager decides to select a sample of 100 customers that need cable service during peak business hours. Specifically, for each of 100 peak business hours, the first customer that starts waiting for customer service rep at or after a randomly selected time during the hour will be chosen.
The mean and the standard deviation of the sample of 100 Time Warner customer waiting times are 5.46 for the sample mean and the standard deviation is 2.475. Use the Empirical Rule and Z-score table to calculate estimates of all possible bank customers waiting times tolerance intervals containing:
a) 68.26 percent,
b) 95.44 percent,
c) 99.73 percent