A woman deposits $12,000 at the end of each year for 15 years in an investment account with a guaranteed interest rate of 6% compounded annually. (a) Find the value in the account at the end of the 15 years. (b) Her sister works for an investment firm that pays 5% compounded annually. If the woman deposits money with this firm instead of the one in part (a), how much will she have in her account at the end of 15 years? (c) How much would she lose or gain over 15 years by investing in her sister's firm