Now let’s look at the productivity of the world’s least productive 80%.
a. How much GDP do they produce?
b. What is the average GDP per capita of the least productive 80% of the world’s population?
c. Now, the payoff: How productive is the average person in the top 20% compared with the average person in the bottom 80% of the planet? Answer this by dividing your answer to question 3c by your answer to question 4b. This chapter and the next are devoted to explaining why this ratio is so large.