Q.4. A random sample was selected from a population having a normal distribution. Calculate a 90% confidence interval estimate for " for each of the following situations: (a). * = 134, n= 10,8 = 3.1 (b). E* = 3,744, n = 120, s = 8.2 (6). * = 40.5, n=9,0 = 2.9