Question

The 95% confidence interval estimate for a population variance when a sample standard deviation of 12 is obtained from a sample of 61 items is

Answer 1

so, from the sample and for this problem we have, n = 61, s= 12,

we want a 95% confidence interval so, level of significance =0.05,

From chi-square table of critical values, we have:

,

so, using these values, 100(1-)%=95% confidence interval for is given by