Question: Marginal Incorporated (MI) has determined that its after-tax cost of debt is 9.0%. Its cost of preferred stock is 13.0%. Its cost of internal equity is 17.0%, and its cost of external equity is 22.0%. Currently, the firm's capital structure has $310 million of debt, $60 million of preferred stock, and $130 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 $97 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 $451 million?