Question

5.6.1. A random sample of size 20 is drawn from a population having a normal distribution. The sample mean and the sample standard deviation from the data are given, respectively, as 2.2 and s-1.42. Construct a 90% confidence interval for the population variance σ2 and interpret.

Answer 1

lower critical value = 10.117

upper critical value =30.144

The 90% confidence interval is 1.271 $< \sigma ^2 <$ 3.7868

we are 90% confident that acual variance lies in this confidence interval