Problem 5-7 Calculating the Number of Periods (L04] At 6.4 percent Interest, how long does it take to double your money? (Do not round Intermediate calculations and round your answer to 2 decimal places, e.g., 32.16.) Length of time years At 6.4 percent interest, how long does it take to quadruple it? (Do not round Intermediate calculations and round your answer to 2 decimal places, e.g., 32.16.) Length of time years