5.103 Charles Thorson has asked you to determine the mean and variance for a portfolio that consists of 100 shares of stock from each of the following firms: 3M Company, Alcoa, Inc., Intel Corporation, Potlatch Corp., General Motors, and Sea Containers. Using the data file Stock Price File, compute the mean and variance for this portfolio. Assuming that the portfolio price is normally distributed determine the narrowest interval that contains 95% of the distribution of portfolio value.