1) Assume a normal distribution with known population variance. Calculate the LCL and UCL for each of the following:

a. 50; 1 = 64;0 = 40; a = 0.05 b. = 85; 1 = 225; 02 = 400; a = 0.01 C. 510; 1 = 485;0= 50;a = 0.107.13 A personnel manager has found that historically the scores on aptitude tests given to applicants for entry- level positions follow a normal distribution with a standard deviation of 32.4 points. A random sample of nine test scores from the current group of applicants had a mean score of 1819 points. a. Find an 80% confidence interval for the population mean score of the current group of applicants. 1:. Based on these sample results. a statistician found for the population mean a condence mterval ex- tending from 165.8 to 210.1] points. Find the con- dence level of this interval.