Problem
Assume a developing country's income per capita is $15,000 and the United States' income per capita is $60,000. If the developing country's income per capita grows at 6% while the United States' income per capita grows is 2%, approximately how long will it take the developing country's income per capita to equal that of the United States? Use the Rule of 72 to arrive at your answer and round your answer to the nearest year.