The 1990s was a remarkably profitable decade for investors in the U.S. stock market. A sample of individual stocks traded during the calendar years 1993, has been examined for the annual rate of return on investment for each stock. (This rate is defined as the percentage of profit relative to investment.) Assume that the annual rate of return is normally distributed. Sample : 1993 stocks 14 stocks were examined. Sample mean annual rate of return = 6.2% Sample standard deviation of annual rates of return = 3.4% Find a 95% confidence interval for the mean annual rate of return for all U.S. stocks traded during 1993