The accompanying table shows the average annual growth rate in real GDP per capita for Argentina, Ghana, and South Korea using data from the Penn World Table, Version 6.2, for the past few decades.

Average annual growth rate of real GDP per capita Years Argentina Ghana South Korea 1960–1970 2.53% 15.54% 7.50%

1970–1980 1.12 0.85 7.62 1980–1990 –2.50 0.10 11.33 1990–2000 3.83 2.08 6.37

a. For each decade and for each country, use the Rule of 70 where possible to calculate how long it would take for that country’s real GDP per capita to double.

b. Suppose that the average annual growth rate that each country achieved over the period 1990–2000 continues indefinitely into the future. Starting from 2000, use the Rule of 70 to calculate, where possible, the year in which a country will have doubled its real GDP per capita.