Which of the following statements is true of the rule of 72? It can be used to determine the amount of time it takes to double an investment. It can be used to estimate approximate compound interest earned for a period of 72 days. It states that the time to double your money (TDM) approximately equals 72/i, where i represents the years it takes to double your investment. It is fairly accurate for interest rates between 25 and 50 percent