Suppose the income tax rate is 0 percent on the first $10,000; 10 percent on the next $20,000; 20 percent on the next $20,000; 30 percent on the next $20,000; and 40 percent on all income above $70,000. Family A has income of $100,000 while Family B has income of $40,000. The marginal tax rates faced by the two families are?a. Family A: marginal20 percent; average10 percent; Family B: marginal40 percent; average23 percent. b. Family A: marginal20 percent; average15 percent; Family B: marginal40 percent; average20 percent. c. Family A: marginal10 percent; average10 percent; Family B: marginal30 percent; average30 percent. d. Family A: marginal20 percent; average20 percent; Family B: marginal40 percent; average40 percent.

Alarge university wanted to study the relationship between completing an internship during college and students' future earning potential. prom the same graduating class, they selected a random sample of 80 students who completed an internship and 100 students who did not complete an internship and examined their salaries five years after graduation. they found that there was a statistically higher mean salary for the internship group than for the noninternship group. which of the following interpretations is the most appropriate? a. there could be a confounding variable, such as student major, that explains the difference in mean salary between the internship and no internship groups. b. we cannot infer anything from these data since the distribution of salaries is likely right skewed. c. you cannot draw any valid conclusions because the sample sizes are different. d. more students should complete internships because having an internship produces a higher salary.