you have just purchased a house and have obtained a 30-year, $200,000 mortgage with an interest rate of 10 percent. what is your annual payment? Assuming you bought the house on January 1, what is the principal balance after 10 years? After four years, mortgage rates drop to 8 percent for 30-year fixed-rate mortgages....Should you refinance your mortgage or invest the $3,000 in a CD