The price per share of stock for sample of 25 companies was recorded at the beginning of 2012 and then again at the end of the 1st quarter of 2012 (The Wall Street Journal, April 2, 2012). How stocks perform during the 1st quarter is an indicator of what is ahead for the stock market and the economy.Use the sample data in the file entitled Stock Prices to answer the following.

a. Let d denote the change in price per share for company i where d-1st quarter of 2012 price per share minus the beginning of 2012 price per share. Use the sample mean of these values to estimate the dollar amount a share of stock as changed during the 1st quarter.

b. What is the 95% confidence interval estimate of the population mean change in the price per share of stock during the first quarter? Interpret this result.

End of 1st Beginning of Company Quarter Year Bank of New York 24.13 68.17 Kraft Foods 38.01 37.36 Dupont 52.90 45.78 Consolidated Edison 58.42 62.03 Johnson & Johnson 65.96 65.58 Union Pacific 107.48 105.94 Comcast 30.01 23.71 Applied Materials 12.45 10.71 Pfiser 43.41 41.22 General Electric 20.07 17.91 AT&T 31.23 30.24 Cisco Systems 21.15 18.08 Home Depot 50.31 42.04 JP Morgan Chase 45.98 33.25 Procter & Gamble 67.21 66.71 Verizon 38.23 40.12 Devon Energy 71.12 62.00 Lilly 40.27 41.56 Microsoft 32.26 25.96 Coco Cola 74.01 69.97 Qualcomm 68.06 54.70 Exxon Mobil 86.73 84.76 Pacific Gas & Electric 22.65 21.64 Oracle Systems 29.16 25.58 Chevron 107.21 106.40