Recall that a bank manager has developed a new system to reduce the time customers spend waiting to be served by tellers during peak business hours. The mean waiting time during peak business hours under the current system is roughly 9 to 10 minutes. The bank manager hopes that the new system will have a mean waiting time that is less than six minutes. The mean of the sample of 90 bank customer waiting times is x = 5.43. If we let mu denote the mean of all possible bank customer waiting times using the new system and assume that sigma equals 2.49: (a) Calculate 95 percent and 99 percent confidence intervals for mu. (Round your answers to 3 decimal places.) (b) Using the 95 percent confidence interval, can the bank manager be 95 percent confident that mu is less than six minutes? Explain. 95 percent interval is 6. (c) Using the 99 percent confidence interval, can the bank manager be 99 percent confident that mu is less than six minutes? Explain. 99 percent interval extends 6. (d) Based on your answers to parts b and c, how convinced are you that the new mean waiting time is less than six minutes? confident, since 95 percent Cl is 6 while 99 percent Cl contains 6.