The mortgage interest rate is the base interest rate plus a floating ratio.

If the base interest rate is 4.9 and increases by 10, the mortgage interest rate is 4.9 × (1 10) = 5.39. After the loan is taken, the floating ratio will not affect the loan amount, only the base interest rate will. The base interest rate may change at any time, but interest rate increases or discounts will follow the loan until it is repaid.