The following data represent the maximal head measurements (across the top of the skull) in millimeters of 15 Etruscans (inhabitants of ancient Etruria).
152 147 126 140 135 139 149 140
142 147 132 148 146 143 137
(a) Calculate an unbiased estimate σˆ 2 of the population variance.
(b) Give approximate 95% con?dence interval for the population variance.
(c) Interpret your results and test for normality.