To answer these questions, use the Penn World Table data available at https://www.rug.nl/ggdc/productivity/pwt/

1. (a)(15 points)Calculate the standard deviation of income per worker for the countries of the world for 1960 and
2. 2007. Does this indicate that convergence is occurring or not? For the same years, calculate the standard deviation of income per worker for the poor countries (less than 20% of income per worker in the United States in 1960) and for the rich countries (greater than 20% of income per worker in the United States in 1960). What does this tell you about convergence among the rich and the poor?
3. (b)Suppose that we divide the countries of the world into three groups: low income per worker in 1960 (less than 33% of income per worker in the United States), middle income per worker in 1960 (between 33% and 67% of income per worker in the United States), and high income per worker in 1960 (greater than 67% of income per worker in the United States).
4. (15 points)Calculate average income per worker for the low income, middle income, and high income countries, respectively, for 1960 and 2007, and calculate the average annual growth rate of average income for the low, middle, and high income countries between 1960 and 2007.
5. (5 points)Do the statistics you calculated in part (i) indicate any tendency for convergence among these three groups of countries?