a. Why are coal miners in China paid higher than factory workers even though they have received more or less the same level of education and training?

b. Why are workers with good looks paid higher in some jobs, but not in others?

c. A recent report released by the Census and Statistics Department indicates that male workers in Hong Kong, on average, earn more than female workers and the gap of wage differential is widening. Is this evidence of sex discrimination? Justify your answer.