Scheer Industries is considering a new computer assisted program to train maintenance employees to do machine repairs. In order to fully evaluate the program, the director of manufacturing requested an estimate of population mean time required for maintenance employees to complete the computer assisted training. Assume that the time for maintenance employees to complete the computer assisted training follows approximately a normal distribution. (a) (4 points) Suppose a large random sample is selected. Based on this sample, a 80% confidence interval for the population mean time required for maintenance employees to complete the computer assisted training is calculated as (48.3, 54.7). Based on this same sample, find a 90% confidence interval for the population mean time required for maintenance employees to complete the computer assisted training. (b) (4 points) Another random sample X1, X2, ..., X6 is selected. Sample statistics show that X1+X2+...+X6 = 300 and (X1)2+ (X2)2 +...+ (X6)2 = 15120. Based on this sample, find a 90% confidence interval for the population mean time required for maintenance employees to complete the computer assisted training