The world's average (mean) GDP per capita is $10,515. There are roughly 7 billion people in the world.
a. What is the world's total GDP?
b. About 20% of the world's population produces 50% of the world's total GDP. (Notice the use of "produces," not "consumes."
In popular discussion, you are more likely to hear about the people at the top "consuming" more than their share, not "producing" more than their share.
But remember what the last letter of GDP stands for!) How much GDP does the top 20% produce?
c. What is the average GDP per capita of the most productive 20% of the world's population?