In a conversation with a friend, you note that you have two real estate investments, one that has doubled in value in the past 9 years and another that has doubled in value in the past 12 years. Your friend says that the first investment has been growing at approximately 8% compounded annually and the second at 6% compounded annually. How did your friend make these estimates? The rule of 72 states that the annual compound rate of growth r of an investment that doubles
in n years can be approximated by r = 72/n. Construct a table comparing the exact rate of growth and the approximate rate provided by the rule of 72 for doubling times of n = 6, 7, . . . ,12 years. Round both rates to one decimal place.