问题如下：
Given the market risk premium is 7% and risk free rate is 4%, please calculate the expected return for security 1 based on CAPM.
选项：
A. 12.0%.
B. 15.2%.
C. 17.5%.
解释：
B is correct.
Based on the CAPM, E(Ri) = Rf + βi[E(Rm)–Rf]
So the expected return of Security 1 equals to
Security 1’s expected return= 4%+1.6*(7%)=15.2%.
答案错了吧，为什么不是4%+1·6*（7%-4%）
