To analyze the risk, or volatility, associated with investing in general electric common stock, a sample of the eight quarterly percent total returns was identified as shown below (charles schwab website, january 2012). the percent total return includes the stock price change plus the dividend payment for the quarter.

20.0 -20.5 12.2 12.6 10.5 -5.8 -18.7 15.3

a. what is the value of the sample mean (to 1 decimal)?
what is its interpretation?
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b. compute the sample standard deviation as a measure of volatility for the quarterly return for general electric (to 2 decimals)?

c. construct a 95% confidence interval for the population variance (to 2 decimals)?
( , )

d. construct a 95% confidence interval for the population standard deviation (to 2 decimals)?
( , )