Mortgage Mechanics Floating Rate Mortgage

Question #3 - Imagine you get a $450,000 closed floating rate mortgage (no CMHC needed) having a three-year term and amortized over 25 years. Although the interest rate on the mortgage would change, your monthly payments would remain fixed for the term. Monthly payments would be calculated based on APR of %4.8 compounded monthly and amortization period of 25 years. The actual amount of the interest accrued will be deducted from your fixed monthly payments and the rest would be used for principal repayment. Now, assume that the floating rate itself is 4.2% for the first 6 months, then suddenly jumps to 6% for the next 12 months, then drops to 3.6% for the next 6 months, and then declines to 3% for the final 12 months. Note that all rates are quoted as an APR and compounded monthly.

Part A: How much money do you owe (i.e. what is the outstanding balance) after 18 months? Part B: How much interest did you pay over the term of the mortgage? How much was principal?