Suppose two countries, Ystan and Zstan start off having the same average per capita (per person) income of $25,000.

a. How large will Ystan's income be in 20 years if the country grows at a rate of 2.3% per year?

b. How large will Zstan's income be in 20 years if the country grows at a rate of 5.2% per year?

c. Ceteris paribus, how many years will it take for each country to double its income if it grows at the same constant rate?

d. What would happen if Ystan to the doubling time if Ystan start going at 15% per year?