To analyze the risk, or volatility, associated with investing in a certain common stock, consider a sample of the eight quarterly percent total returns. The percent total return includes the stock price change plus the dividend payment for the quarter. 11.2 -21.5 11.2 12.6 11.5 -5.8 -18.7 16.3 (a) What is the value of the sample mean (as a percent)? What is its interpretation? The value is 2.075 X%, which is the estimate of the population mean percent total return per quarter for this stock. (b) Compute the sample variance and sample standard deviation (as a percent) as measures of volatility for the quarterly return for this stock. (Round your answers to two decimal places.) variance standard deviation x X% (c) Construct a 95% confidence interval for the population variance. (Round your answers to two decimal places.) to X (d) Construct a 95% confidence interval for the population standard deviation (as a percent). (Round your answers to two decimal places.) X % to %