You would like to have $ 50000 in 15 years. To accumulate this amount you plan to deposit each year an equal amount in the bank, which will earn 7 percent interest compounded annually. Your first payment will be made at the end of the year. a) How much must you deposit annually to accumulate this amount? b) If you decide to make a large lump-sum deposit today instead of the annual deposit, how large should this lump-sum deposit be? (Assume you can earn 7 percent on this deposit)