A person's credit score is important in determining the interest rate on a home mortgage. According to Consumer Credit Counseling Service, a home-owner with a $100,000 mortgage and a 520 credit score will pay $110, 325 more in interest charges over the life of a 30-year loan than a homeowner with the same mortgage and a credit score of 720. How much higher would the interest rate per year have to be in order to account for this much difference in interest charges, if the $100,000 loan is repaid in a single lump-sum payment at the end of 30 years