a. If the interest rate is 7.4% per year, approximately how long will it take for your money to quadruple in value? (Use the Rule of 72.) Number of years b. If the inflation rate is 4.7% per year, what will be the change in the purchasing power of your money over this period? (Use the Rule of 72 to compute the number of years. Do not round intermediate calculations. Enter your answer as a percent rounded to 2 decimal places.) Purchasing power by %