For this part, you MUST present sufficient solution sters, and MUST apply specific Excel functions =PV(...). =FV[...). =PMT(...). =NPERC...). =RATE..... =PRICE...) or =YIELD(...) whenever applicable. Otherwise, you will get very heavy deductions in credit points, no matter whether your final answer amounts are correct or not.) Case 1: You apply for a 15-year, fixed-rate (APR 3.72%) monthly-payment-required mortgage loan for a house selling for $135,000 today. Your bank requires 22% initial down payment of house value to be paid upfront in cash immediately, thus not included in the loan balance), therefore lends you the remaining 78% of house value as the loan, plus $3,000 application process-closing cost (to be added into the beginning loan balance and amortized later). (a) What is your monthly loan payment if you stick to the mortgage deal till the end, assuming each payment is made at the end of each month? (b) 7 years (i.e., 84 months, please note again that it is a monthly mortgage) after buying the house, what will be the remaining loan principal balance? (e) 7 years (i.e., 84 months) after buying the house, the mortgage loan market rate drops from 3.72% APR to 3.48% APR. You think about the option of refinancing to save money, but do not want to do the 15-year mortgage all over again, only want to refinance on the remaining loan principal balance for the remaining loan life period. Refinancing is not free, because the bank would charge an extra refinancing fee of $1,500, to be added into the remaining loan principal balance for amortization later. If you choose to refinance, would you be able, and by how much to lower your monthly loan payment and thus save money? Based on your calculation results, should you choose to refinance or not? (d) Redo the calculations in Question (e), this time assuming that the loan market rate drops from 3.72% APR to 2.76% APR (instead of 3.48%), and the refinancing fee charged by the bank becomes $1,000 (instead of $1,500). Should you refinance or not then