$36$ When he tumed $65$ years old, Alberto used his savings of $$50,000$ to purchase a term certain annuity to age $90.$ As a result, he will receive payments of $$330$ at the beginning of each month. What is the nominal annual interest rate with monthly compounding that this investment yields?

a$)6\mathrm{.}17\%$

b$)6\mathrm{.}31\%$

c$)6\mathrm{.}50\%$

$4)7\mathrm{.}12\%$