A research analyst is examining a stock for possible inclusion in his client's portfolio. Over a 19-year period, the sample mean and the sample standard deviation of añnual returns on the stock were...

Extracted text: A research analyst is examining a stock for possible inclusion in his client's portfolio. Over a 19-year period, the sample mean and the sample standard deviation of añnual returns on the stock were 21% and 15%, respectively. The client wants to know if the risk, as measured by the standard deviation, differs from 18%. (You may find it useful to reference the appropriate table: chi-square table or F table) a. Construct the 90% confidence intervals for the population variance and the population standard deviation. (Round intermediate calculations to at least 4 decimal places and final answers to 2 decimal places.) Confidence Intervals Population variance Population standard deviation to to b. What assumption did you make in constructing the confidence intervals?