A CEO says that he prefers his company to hire graduates from state schools rather than private schools

A CEO says that he prefers his company to hire graduates from state schools rather than private schools. He claims that state school graduates are a better fit for his company, and hence more productive. To back up his claim, he shows you data on 38 new hires from the last 20 years, and their salaries after 10 years. Higher productivity implies higher salary (hopefully!) so you test to see whether or not the salary of the state school graduates (population 1) is higher than that of private school graduates (population 2). The data are summarized below (dollar values in $1000s). Group Sample size Average salary Standard deviation State School 23 $79 $27 Private School 15 $72 $17 Assume that the variance in the two groups is not equal. Under the null hypothesis of no difference in salary, what is the distribution of the test statistic that you would use to test that the salary is higher among the state school graduates. Select one: O a. A z-distribution O O b. A t-distribution with 38 degrees of freedom c. A t-distribution with 37 degrees of freedom d. A t-distribution with 36 degrees of freedom e. A t-distribution with 35 degrees of freedom O