Fortune magazine (March 1997) reported the total returns to investors for the 10 years prior to 1996 and also for 1996 for 431 companies. The total returns for 10 of the companies are listed below. Find a 87% confidence interval for the mean change in percent return to investors. Total Return to Investors Company 1986-1996 1996 Coca-Cola 29.8% 43.3% Mirage Resorts 27.9% 25.4% Merck 22.1% 24.0% Microsoft 44.5% 88.3% Johnson