(solving for r with annuities) nicki johnson, a sophomore mechanical engineering student, receives a call from an insurance agent, who believes that nicki is an older woman ready to retire from teaching. he talks to her about several annuities that she could buy that would guarantee her an annual fixed income. the annuities are as follows: annuity initial payment into annuity (at t = 0) amount of money received per year duration of annuity (years) a $50 comma 00050,000 $6 comma 5006,500 1818 b $70 comma 00070,000 $8 comma 5008,500 2020 c $50 comma 00050,000 $9 comma 0009,000 1010 if nicki could earn percent on her money by placing it in a savings account, should she place it instead in any of the annuities? which ones, if any? why?