CHALLENGE ACTIVITY 6.2.1: Confidence intervals for population means. 402462.2600164.qx3zqy7 Jump to level 1 1 Suppose the mean height in inches of all 9th grade students at one high school is 2 estimated. The population standard deviation is 5 inches. The heights of 9 randomly selected students are 62, 65, 74, 64, 73, 69, 67, 73 and 62. T = 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]