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 $1 million of retained earnings with a cost of rs = 12%. New common stock in an amount up to $10 million would have a cost of re = 13.5%. Furthermore, Olsen can raise up to $3 million of debt at an interest rate of rd = 11% and an additional $4 million of debt at rd = 15%. The CFO estimates that a proposed expansion would require an investment of $4.2 million. What is the WACC for the last dollar raised to complete the expansion? Round your answer to two decimal places.