Suppose the mean height in inches of all 9th grade students at one high school is estimated. The population standard deviation is 4 inches. The heights of 7 randomly selected students are 61, 71, 73, 64, 63, 64 and 70. F=Ex:1234 Margin of error at 90% confidence level = Ex: 1.23 90% confidence interval = [ Ex: 12.34 . Fx: 1234 1] [smaller value, larger value]