CHALLENGE ACTIVITY 6.2.1: Confidence intervals for population means. 376966.2013306.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 2 inches. The heights of 6 randomly selected students are 72, 62, 75, 65, 73 and 60. T = Ex: 12.34 Margin of error at 95% confidence level = Ex: 1.23 95% confidence interval = [ Ex: 12.34 Ex: 12.34 [smaller value, larger value]