The interest rate of the provident fund is 3: 1, which means 500,000 yuan for three years, and the annual interest rate is 1550 yuan. According to the repayment rate of the provident fund of 3. 1%, the repayment amount of 500,000 yuan and the repayment period of 3 years, one-year interest can be calculated by using the following formula: one-year interest = repayment amount × repayment rate = 500,000× 3.1%=1550 yuan. Therefore, the provident fund with a repayment period of 3 years and a repayment period of 1 year,