问题如下图：
选项：
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解释：
请问第二问的问题是什么意思？这里为什么需要做一个t-test，检验的目的是什么？谢谢~
NO.PZ2016071602000001问题如下Over the past year, the HIR Funha return of 7.8%, while its benchmark, the S P 500 inx, ha return of 7.2%. Over this perio the funs volatility w11.3%, while the S P inx's volatility w10.7% anthe funs TEV w1.25%. Assume a risk-free rate of 3%. Whis the information ratio for the HIR Funanfor how many years must this performanpersist to statistically significant a 95% confinlevel?A.0.480 anapproximately 16.7 yearsB.0.425 anapproximately 21.3 yearsC.3.840 anapproximately 0.2 years1.200 anapproximately 1.9 yearsA is correct. The information ratio is (7.8 — 7.2)/1.25 = 0.48. Statisticsignificanis achievewhen the t-statistic is above the usuvalue of 1.96. Equation (29.5), the minimum number of years T for statisticsignificanis (1.96/IR)2 = 16.7. Note, however, ththere is no neeto perform the seconcomputation because there is only one correanswer for the IR question.TEV/跟号N是标准误吗
NO.PZ2016071602000001问题如下Over the past year, the HIR Funha return of 7.8%, while its benchmark, the S P 500 inx, ha return of 7.2%. Over this perio the funs volatility w11.3%, while the S P inx's volatility w10.7% anthe funs TEV w1.25%. Assume a risk-free rate of 3%. Whis the information ratio for the HIR Funanfor how many years must this performanpersist to statistically significant a 95% confinlevel?A.0.480 anapproximately 16.7 yearsB.0.425 anapproximately 21.3 yearsC.3.840 anapproximately 0.2 years1.200 anapproximately 1.9 yearsA is correct. The information ratio is (7.8 — 7.2)/1.25 = 0.48. Statisticsignificanis achievewhen the t-statistic is above the usuvalue of 1.96. Equation (29.5), the minimum number of years T for statisticsignificanis (1.96/IR)2 = 16.7. Note, however, ththere is no neeto perform the seconcomputation because there is only one correanswer for the IR question.16.7是怎么出来的
NO.PZ2016071602000001 不懂第二个答案16.7年是怎么计算得到
NO.PZ2016071602000001 如果题目中没有说明到底是Jensen's alpha还是正常的alpha，而题目中求Jensen's alpha条件又齐全应该用哪种方法求呢？
the minimum number of years T for statisticsignificanis (1.96/IR)2 = 16.7 这个是从哪个公式推导出来的？
