I (b) Compute the 95% condence interval estimate of the Population variance. A confidence interval for the population variance 0-2 will have the following form where n is the sample size and 52 is the sample variance. The 12 values correspond to a chi-square distribution with n 1 degrees of a a freedom where _ and 1 _ are the upper tail areas. 2 2 (n 1)s2 2 (n l)s2 25 9' 52 J{at/2 1]. 11/2 Recall that the value of alpha is found by setting the condence level equal to (1 at) and solving for a. A 95% confidence interval is to be found. Expressing 95% as a probability gives 0.95, so we have 1 a: = 0.95. Therefore, a = 0.05, so ; = and 1 g = The sample size is n = 20, so the degrees of freedom is n 1 =