cost of equity 公式没看懂

问题如下：

3. Using the capital asset pricing model, the cost of equity capital for a company in this industry with a debt-to-equity ratio of 0.01, asset beta of 2.27, and a marginal tax rate of 23 percent is closest to:

选项：

17 percent.

21 percent.

24 percent.

解释：

B  is correct.

Asset beta = 2.27

Levered beta = 2.27 {1 + [(1 − 0.23)(0.01)]} = 2.2875

Cost of equity capital = 0.0525 + (2.2875)(0.07) = 0.2126 or 21.26%