Question

The waiting times​ (in minutes) of a random sample of 20 people at a bank have a sample standard deviation of 4.4 minutes. Construct a confidence interval for the population variance sigma squared and the population standard deviation sigma. Use a 90 % level of confidence. Assume the sample is from a normally distributed population. What is the confidence interval for the population variance sigma squared​? ​( nothing​, nothing​) ​(Round to one decimal place as​ needed.) Interpret the results. Select the correct choice below and fill in the answer​ box(es) to complete your choice. ​(Round to one decimal place as​ needed.) A. With 10​% ​confidence, you can say that the population variance is greater than nothing. B. With 90 % ​confidence, you can say that the population variance is between nothing and nothing. C. With 10​% ​confidence, you can say that the population variance is between nothing and nothing. D. With 90 % ​confidence, you can say that the population variance is less than nothing. What is the confidence interval for the population standard deviation sigma​? ​( nothing​, nothing​)​ (Round to one decimal place as​ needed.) Interpret the results. Select the correct choice below and fill in the answer​ box(es) to complete your choice. ​(Round to one decimal place as​ needed.) A. With 90​% ​confidence, you can say that the population standard deviation is greater than nothing minutes. B. With 10​% ​confidence, you can say that the population standard deviation is between nothing minutes and nothing minutes. C. With 90​% ​confidence, you can say that the population standard deviation is between nothing and nothing minutes. D. With 10​% ​confidence, you can say that the population standard deviation is less than nothing minutes. Click to select your answer(s).

Answer 1

The required confidence interval for population variance is (12.2, 36.4),

B. With 90 % ​confidence, you can say that the population variance is between 12.2 and 36.4.

---------------------------------------------

The required confidence interval for population variance is (3.5, 6.0),

C. With 90​% ​confidence, you can say that the population standard deviation is between 3.5 and 6.0 minutes.