Marginal Incorporated $($MI$)$ has determined that its after$-$tax cost of debt is $10\mathrm{.}0\%.$ Its cost of preferred stock is $14\mathrm{.}0\%.$ Its cost of internal equity is $16\mathrm{.}0\%,$ and its cost of external equity is $19\mathrm{.}0\%.$ Currently, the firm's capital structure has $$325$ million of debt, $$50$ million of preferred stock, and $$125$ million of common equity. The firm's marginal tax rate is $45\%.$ The firm is currently making projections for the next period. Its managers have determined that the firm should have $$62$ million available from retained earnings for investment purposes next period. What is the firm's marginal cost of capital at a total investment level of $$298$ million?

$12\mathrm{.}28\%$

$11\mathrm{.}90\%$

$12\mathrm{.}65\%$

$9\mathrm{.}73\%$

$8\mathrm{.}98\%$