PLEASE ANSWER ALL THREE QUESTIONS YOU WILL GET THUMBS UP$!$

a$)$ The management of Gibraltar Brokerage Services anticipates a capital expenditure of$$$$25,000$in$2$years for the purchase of new computers and has decided to set up a sinking fund to finance this purchase. If the fund earns interest at the rate of$3\%/$year compounded quarterly, determine the size of each $($equal$)$ quarterly installment that should be deposited in the fund.$$

B$)$ Jessica wants to accumulate$$$$15,000$by the end of$4$years in a special bank account, which she had opened for this purpose. To achieve this goal, Jessica plans to deposit a fixed sum of money into the account at the end of the month over the$4-$year period. If the bank pays interest at the rate of$7\%$per year compounded monthly, how much does she have to deposit each month into her account?$$

C$)$ Andrea, a self$-$employed individual, wishes to accumulate a retirement fund of$$$$650,000.$ How much should she deposit each month into her retirement account, which pays interest at a rate of$2\mathrm{.}5\%/$year compounded monthly, to reach her goal upon retirement$40$years$$from now?