13. It has been reported that 91% of federal government employees use e-mail. If a sample of 240 federal government employees is selected, find the mean, variance, and standard deviation of the number who use e-mail. a. Find the mean. b. Find the variance. c. Find the standard deviation. 14. Seventy percent of Americans favor spending government money to develop alternative sources of fuel for automobiles. For a random sample of 135 Americans, find the mean, variance, and standard deviation for the number who favor government spending for alternative fuels. a. Find the mean. b. Find the variance. c. Find the standard deviation