4) A family buys a new house using a $200,000 mortgage at i(12) = 5.4% . They plan to repay the mortgage with payments made at the end of each month for 25 years. a) Find their monthly payment b) Assuming that they follow the amortization schedule, find the outstanding balance on the loan at the end of the 4th year (immediately after the 48th payment). c) Find the amounts of interest and principal paid in the 49th payment, based on the original payment schedule. d) If they made an additional payment of $30,000 at the end of the 4th year but kept their remaining payment amount at the level calculated in part a), when do they expect to pay the loan off?