6.76 Financial aid.
The fnancial aid office of a university asks a sample of students about their employment and earnings. The report says that “for academic year earnings, a signifcant difference was found between the sexes, with men earning more on the average. No difference was found between the earnings of black and white students.”18 Explain both of these conclusions, for the effects of sex and of race on mean earnings, in language understandable to someone who knows no statistics.