20.value: 5.00 points The Rule of 72 is a useful approximation for many interest rates and periods for the time it takes a lump sum to double in value. For a 10 percent interest rate, calculate the time that will be taken for a lump sum to double in value. (Hint: Use the Solver function in Excel.) (Round your answer to 2 decimal places. (e.g., 32.16))