A bond has a coupon rate of $7\mathrm{.}5\%,$ pays interest semiannually, sells for $$950,$ and matures in $15$ years. What is its yield to maturity?

a$.$

$8\mathrm{.}0812\%$

b$.$

$4\mathrm{.}0406\%$

c$.$

$7\mathrm{.}9417\%$

d$.$

$8\mathrm{.}0873\%$