EU (European Union) countries report that 46% of their labor force is female. The United Nations wants to determine if the percentage of females in the U.S. labor force is the same. Based on a sample of 500 employment records, representatives from the United States Department of Labor found that the 95% confidence interval for the proportion of females in the U.S. labor force is .357 to.443. If the Department of Labor wishes to tighten its interval, they should O both increase the confidence level and increase the sample size. O Increase the confidence level. O decrease the sample size. increase the sample size. both increase the confidence level and decrease the sample size