Question

6) In a study of starting salaries for nurses, I surveyed 20 nurses. In this sample, the starting salary was $70,000 with a standard deviation of $8,000.

(a) (10pts) Develop a 95% confidence interval for the population mean.

(b) (10pts) Develop a 95% confidence interval for the population standard deviation.

Please write out. Thank you man!

Answer 1

Using t-table, the critical value for two-tail test at 5% significance level and degrees of freedom, df = n-1 = 19 is t* = 2.093. Hence the confidence interval of population mean is obtained as

For confidence interval of population standard deviation, we use chi-square distribution.

Substituting the values,