$7\mathrm{.}4.$ Pam promises to pay Sandy $$4,000$ in year $4$ and another $$6,000$ in year $8$ for a loan of $$4,000$

from Sandy today. What is the ROR that Sandy is getting? Assume interest is compounded monthly.

A$)14\mathrm{.}75\%$

B$)16\mathrm{.}72\%$

C$)15\mathrm{.}39\%$

D$)18\mathrm{.}08\%$