Problem 2. (It) points, 2 parts) Executive compensation has risen dramatically com pared to the rising levels of an average worker"s wage over the years. Sarah is an MBA student who decides to use her statistical skills to estimate the mean CEO compensation in 2(122 for all large companies in the Unites States. She takes a random sample of 18 CEO compensations {in '35 millions). The data are in the le \"ceo_con1pensation_18.xlsx". a.) Help Sara: use the data to construct the 95% condence interval for the mean CEO compensation for all large companies in the United States. b) What main assumption is necessary here for deriving the interval estimate?