Gekko Industries plans to issue a $$1,000$ par, semi$-$annual pay bond with $20$ years to maturity and a coupon rate of $7\mathrm{.}00\%.$ The company expects the bonds to sell for $$820\mathrm{.}00.$ MC Inc's cost of debt is estimated to be $\_\_\_\_\_\_\_\%.$

Question $11$ options:

$8\mathrm{.}702$

$8\mathrm{.}949$

$8\mathrm{.}511$

$8\mathrm{.}390$

$9\mathrm{.}163$