GE 4.7.1: Confidence intervals for population means. Jump to level 1 Suppose the mean height in inches of all 9th grade students at one high school is estimated. The population standard deviation is 2 inches. The heights of 7 randomly selected students are 65, 63, 74, 69, 69, 64 and 64. = Ex: 12.34 : Margin of error at 99% confidence level = Ex: 1.23 99% confidence interval = [ Ex: 12.34 Ex: 12.34 [smaller value, larger value] Check Next