问题如下图：
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解释：
老师，least amount of market risk为什么用beta衡量？beta衡量的不是系统性风险吗？
NO.PZ2015121801000094问题如下 analyst gathers the following information:Whisecurity hthe least amount of market risk?A.Security 1.B.Security 2.C.Security 3.is correct.Security 2 hthe lowest beta value; 0.93 = ρ 2 m σ 2 σ m = ( 0.70 ) ( 20 % ) 15 % compareto Security 1 an3 with beta values of 1.00 an1.07, respectively.还是不太懂。能不能麻烦老师完整的讲一遍呢。谢谢
NO.PZ2015121801000094问题如下analyst gathers the following information:Whisecurity hthe least amount of market risk?A.Security 1.B.Security 2.C.Security 3.is correct.Security 2 hthe lowest beta value; 0.93 = ρ 2 m σ 2 σ m = ( 0.70 ) ( 20 % ) 15 % compareto Security 1 an3 with beta values of 1.00 an1.07, respectively.这样最后算出来的收益率R也是最高的
NO.PZ2015121801000094问题如下analyst gathers the following information:Whisecurity hthe least amount of market risk?A.Security 1.B.Security 2.C.Security 3.is correct.Security 2 hthe lowest beta value; 0.93 = ρ 2 m σ 2 σ m = ( 0.70 ) ( 20 % ) 15 % compareto Security 1 an3 with beta values of 1.00 an1.07, respectively.market risk 不是totrisk吗
NO.PZ2015121801000094问题如下 analyst gathers the following information:Whisecurity hthe least amount of market risk?A.Security 1.B.Security 2.C.Security 3.is correct.Security 2 hthe lowest beta value; 0.93 = ρ 2 m σ 2 σ m = ( 0.70 ) ( 20 % ) 15 % compareto Security 1 an3 with beta values of 1.00 an1.07, respectively.这种计算用的是那个公式
NO.PZ2015121801000094 问题如下 analyst gathers the following information:Whisecurity hthe least amount of market risk? A.Security 1. B.Security 2. C.Security 3. is correct.Security 2 hthe lowest beta value; 0.93 = ρ 2 m σ 2 σ m = ( 0.70 ) ( 20 % ) 15 % compareto Security 1 an3 with beta values of 1.00 an1.07, respectively. 解析中 0.93=�2��2��=(0.70)(20%)15% 这个公式beta的公式不应该是cov（1，2）/0.15的平方吗？为什么解析中会这样算的
