问题如下图：
CFA二级equity的序号8021题第（8）问，为什么ROE等于required rate o return？谢谢！
选项：
A. 
B. 
C. 
解释：
NO.PZ201710200100000208 问题如下 8. Baseon Exhibit 4 anIntern 1’s analysis, Xavier Corporation’s sustainable vinpayout ratio is closest to: A.43.4%. B.44.6%. C.56.6%. C is correbecause it is baseon the sustainable growth rate anthe requirerate of return:Sustainable growth rate = (b in mature phase) × (Return on equity) = (1 – vinpayout) × (Return on equity) 0.036 = (1 – vinpayout) × 0.083Solving for the vinpayout ratio, the vinpayout = 56.627% ≈ 56.6%. 亏我还想了半天，一看答案直接用re当roe用，简直了
NO.PZ201710200100000208 老师 requirerate of return=ROE？
NO.PZ201710200100000208 公司处于成熟阶段，因此可以ROE近似等于r, 这可以当结论记的是吗？ 谢谢。
44.6%. 56.6%. C is correbecause it is baseon the sustainable growth rate anthe requirerate of return: Sustainable growth rate = (b in mature phase) × (Return on equity) = (1 – vinpayout) × (Return on equity) 0.036 = (1 – vinpayout) × 0.083 Solving for the vinpayout ratio, the vinpayout = 56.627% ≈ 56.6%.看了之前老师的，没有看懂，想再问一下为啥不能用Re=P+g的公式反推vinpayout ratio？
老师好为什么这题不能用re=(/P0)+g的公式来求vintpayoutratio?谢谢。
