问题如下图：
选项：
A. 
B. 
C. 
解释：
这题为就算到0.23就卡住了。
想问一下，safety first ratio算出来的0.23是一个什么值？老师说在T分布表，解析说查cdf表，到底查什么表？
感谢解答。
NO.PZ2017092702000088 问题如下 A portfolio hexpectereturn of 7% with a stanrviation of 13%. For investor with a minimum annureturn target of 4%, the probability ththe portfolio return will fail to meet the target is closest to: A.33%. B.41%. C.59% B is correct.B is correct. using Excel's NORM.S. ST() function, we get NORM.S. ST((4%-7%)/13%) = 40.87%. The probability ththe portfolio willl unrperform the target is about 41%.本题要求的P(X＜4%)的概率。第一步先做标准化后才能查表。然后代入标准化的公式即可。-------------------------------------------------------------------------There are three steps, whiinvolve stanrzing the portfolio return: First, subtrathe portfolio mereturn from easi of the inequality: P(Portfolio return – 7%) ≤ 4% – 7%). Secon vi easi of the inequality the stanrviation of portfolio return: P[(Portfolio return – 7%)/13% ≤ (4% – 7%)/13%] = P(Z ≤ –0.2308) = N(–0.2308). Thir recognize thon the left-hansi we have a stanrnormvariable, noteZ anN(–x) = 1 – N(x). Rounng –0.2308 to –0.23 for use with the cumulative stribution function (c) table, we have N(–0.23) = 1 – N(0.23) = 1 – 0.5910 = 0.409, approximately 41 percent. The probability ththe portfolio will unrperform the target is about 41 percent. 求问这道题0.59是不是要靠查表啊？题目没有给出表是不是就无法求出0.59?
NO.PZ2017092702000088 问题如下 A portfolio hexpectereturn of 7% with a stanrviation of 13%. For investor with a minimum annureturn target of 4%, the probability ththe portfolio return will fail to meet the target is closest to: A.33%. B.41%. C.59% B is correct.B is correct. using Excel's NORM.S. ST() function, we get NORM.S. ST((4%-7%)/13%) = 40.87%. The probability ththe portfolio willl unrperform the target is about 41%.本题要求的P(X＜4%)的概率。第一步先做标准化后才能查表。然后代入标准化的公式即可。-------------------------------------------------------------------------There are three steps, whiinvolve stanrzing the portfolio return: First, subtrathe portfolio mereturn from easi of the inequality: P(Portfolio return – 7%) ≤ 4% – 7%). Secon vi easi of the inequality the stanrviation of portfolio return: P[(Portfolio return – 7%)/13% ≤ (4% – 7%)/13%] = P(Z ≤ –0.2308) = N(–0.2308). Thir recognize thon the left-hansi we have a stanrnormvariable, noteZ anN(–x) = 1 – N(x). Rounng –0.2308 to –0.23 for use with the cumulative stribution function (c) table, we have N(–0.23) = 1 – N(0.23) = 1 – 0.5910 = 0.409, approximately 41 percent. The probability ththe portfolio will unrperform the target is about 41 percent. 請問這題爲何最終沒有用1-40.90%，謝謝
NO.PZ2017092702000088 老师，题目中的7%为预期回报，怎么就把他当做公式中的均值了呢？
NO.PZ2017092702000088 老师，看到这道题我第一思路是E（Rp）=7%，方差=13%，Rl=4%，可求出SFR=23%。题目问 target fali，我理解意思是寻找SFR＞23%的数字，因为这样Rl就会＜4%，没有达到minimize的要求，我陷在这个思路里出不来了，没有想到用标准化公式。请老师帮忙指点迷津，谢谢！
NO.PZ2017092702000088 我想问的是u为什么是百分之7，u是均值，这里的%7不是return吗？？？
