In: Statistics and Probability
In a state, 50,000 students graduated from four-year not for profit colleges in 2019. Out of these 50,000 graduates, 20,000 students graduated from private colleges, and 30,000 students graduated from public colleges. You have selected a stratified sample from the population of 2019 graduates in this state with graduates from private and public colleges as the two strata. For each graduate in your sample, you recorded how much student debt, if any, the graduate carried at graduation. The results are as follows: (1) Private college graduates: n1 = 400, X-bar-1 = 33,000, s1 = 15,000 (2) Public college graduates: n2 = 100, X-bar-2 = 26,400, s2 = 6000 2(a) At a 99% level of confidence, test the null hypothesis that the total debt of the 20,000 private college graduates, combined, did not exceed $600,000,000. 2(b) At a 99% level of confidence, test the null hypothesis that the average debt of a private college graduate did not exceed the average debt of a public college graduate by more than $5000.