🐚 · 2022年10月08日
NO.PZ2015120604000095
问题如下：
A fund manager finds that the return of funds in the market are normally distributed having a mean of $160,000 and a standard deviation of $30,000. What is the percent of return that are less than $100,000 ?
选项：
A.0.05%.
B.0.13%.
C.2.28%.
解释：
C is correct.
z = (100000- 160000) /30000 = -2,
F(-2) = 1 - F(2)= 1 - 0.9772 = 0.0228
1:不懂为什么需要1减去F(-2)
2: 为什么我查的z table里的-2 = 0.02275
NO.PZ2015120604000095 问题如下 A funmanager fin ththe return of fun in the market are normally stributehaving a meof $160,000 ana stanrviation of $30,000. Whis the percent of return thare less th$100,000 ? A.0.05%. B.0.13%. C.2.28%. C is correct.z = (100000- 160000) /30000 = -2,F(-2) = 1 - F(2)= 1 - 0.9772 = 0.0228 RT
NO.PZ2015120604000095 0.13%. 2.28%. C is correct. z = (100000- 160000) /30000 = -2, F(-2) = 1 - F(2)= 1 - 0.9772 = 0.0228 从1.96倍标准差95%的依据，均值160K刚好减去2倍标准差（30*2）是100K，为何这个5%比1-F（2）大很多？
NO.PZ2015120604000095 我怎么知道F2就是0.97？？？？考试不给我表我怎么知道？？必须记住F2等于多少吗？
我后面都理解，但是第一步求z值忘记了，这是固定公式吗？
