a$)$ 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? $($Round your answer to the nearest cent.$)$

B$)$ 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.