Problem set 1: Use the following data to answer questions 1-3 (30 points): Mean Standard Deviation N Lower class 11.61 2.67 196 Working class 12.80 2.85 626 Middle class 14.45 3.08 484 Upper class 15.45 4.05 60 The 2010 GSS provides these statistics above for the average years of education for lower-, working-, middle-, and upper-class respondents and their associated standard deviations. 1. Construct the 90% confidence interval for the mean number of years of education for lower-class and midd