Look at the spot interest rates shown $($r$1=4\mathrm{.}6\%,$ r$2=4\mathrm{.}4\%,$ r$3=4\mathrm{.}2\%,$ and r$4=4\mathrm{.}0\%)$ Suppose that someone told you that the five$-$year spot interest rate was $2\mathrm{.}5\%.$ Why would you not believe him? How could you make money if he was right? What is the minimum sensible value for the five$-$year spot rate?