6. Calculating Interest Rates [LO3] Assume the total cost of a college education will be $345,000 when your child enters college in 18 years. You presently have $73,000 to invest. What annual rate of interest must you earn on your investment to cover the cost of your child's college education? -73000 RATE PV Periods FV 18 345000 7. Calculating the Number of Periods [LO4] At 6.1 percent interest, how long does it take to double your money? To quadruple it? -100 RATE PV NPER FV RATE -100 PV NPER 200 FV 400