Company A's historical returns for the past three years were 6 percent, 15 percent, and 15 percent. Similarly, the market portfolio's returns were 10 percent, 10 percent, and 16 percent. Suppose the risk-free rate of return is 4 percent and that investors expect the market to return 10 percent. What is the cost of equity capital (required rate of return of company A's common stock), computed with the CAPM?