Olsen Outfitters Inc. believes that its optimal capital structure consists of 55% common equity and 45% debt, and its tax rate is 40%. Olsen must raise additional capital to fund its upcoming expansion. The firm will have $4 million of retained earnings with a cost of . New common stock in an amount up to $8 million would have a cost of . Furthermore, Olsen can raise up to $4 million of debt at an interest rate of and an additional $5 million of debt at . The CFO estimates that a proposed expansion would require an investment of $8.2 million. What is the WACC for the last dollar raised to complete the expansion?