7. Mr. Goo makes 20 beginning of year deposits in to a college fund crediting interest at an annual effective rate of 5%. Each of the first 10 deposits is 1000, and each of the second 10 deposits is 2000. Starting n years after his final deposit, the fund makes annual withdrawals of 6000 forever. (a) Find the smallest possible value for n. (b) Is it possible to squeeze in a smaller withdrawal n - 1 years after the final deposit? If so, what is the amount? Take the n to be the same value as in part (a)