Internationally, Gini coefficient is a measure of income inequity. It is between zero and one.

(a) Please use your language or graphs to show how to measure Gini Coefficient?

(b) After a study about the income bracket in the US, you found the household real income of middle class, e.g. $50,000 to $99,000 has been decreasing in the percentage of total population in the past 20 years. But the share of high-income ($100,000 and above) has increasing over time. How this change would affect the US Gini coefficient? Please present details of your answer.