Assume the total cost of a college education will be $300,000 when your child enters college in 18 years. You presently have $63,000 to invest. What annual rate of interest must you earn on your investment to cover the cost of your child's college education? (Do not round intermediate calculations. Enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) Annual rate of interest At 5.5 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 5.5 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