A firm has determined its cost of each source of capital (before considering tax) and optimal capital structure, which is composed of the following sources and target market value proportions: The firm's marginal tax rate is 40%. The weighted average cost of capital is 6 percent 7.33 percent 11 percent The firm's marginal tax rate is 40%. The weighted average cost of capital is 6 percent 7.33 percent 11 percent 15 percent 5.04 percent