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. 13.2 -19.5 11.2 11.6 11.5 -6.8 -19.7 15.3 (a) what is the value of the sample mean (as a percent)? what is its interpretation? the value is %, 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 (c) construct a 95% confidence interval for the population variance. (round your answers to two decimal places.) to (d) construct a 95% confidence interval for the population standard deviation (as a percent). (round your answers to two decimal places.) % to