$4.)$ John and Mary want to start saving for retirement.

a$.)$ They invest $$1565$ each quarter in a mutual fund that pays $12\%$ compounded

quarterly. How much will they have after $25$ years?

b$.)$ In retirement, they want to take equal monthly withdrawals for $20$ years

reducing the balance to zero. What is the size of each withdrawal?

c$.)$ How much interest will they earn over the entire $45$ year process?