4. Suppose that you purchase a special 2-year annuity. This annuity pays you $X every month except only for July. You will receive $2x in July because of your birthday. If you are willing to pay $15,000 today for this special annuity, what is $X? Assume that the interest rate is 3%(12) and the payment is made at the beginning of each month. a. $412.62 b. $593.70 c. $687.41 d. $349.68 5. Suppose that you take a 30-year mortgage loan at 12%(12) and your monthly payment (ordinary annuity) is $R. Find your outstanding balance in 14 years. a. Ra168|1% b. Ra192[1% C. RS168|1% d. RS192|1% 6. Find the PV of an annuity-due that pays $630 per quarter for 7.5 years at 10%(4). a. $10,628.92 b. $11,516.78 c. $12,148.35 d. $13,515.74