March 4, 2009, was one of the few good days for the stock market in early 2009. The Dow Jones Industrial Average went up 149.82 points (The Wall Street Journal, March 5, 2009). The following table shows the stock price changes for a sample of 12 companies on that day.

a. Compute the sample variance for the daily price change.
b. Compute the sample standard deviation for the price change.
c. Provide 95% confidence interval estimates of the population variance and the population standard deviation.

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Price Change Price Change Company Aflac Bank of Am. Cablevision Diageo Flour Cp Goodrich 0.81 -0.05 0.41 1.32 2.37 0.3 Company John.&John. Loews Cp Nokia SmpraEngy Sunoco Tyson Food 1.46 0.92 0.21 0.97 0.52 0.12