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顾思萌要加油 · 2024年03月13日

25%*20%这2个数是哪里得来的

NO.PZ2020010304000017

问题如下:

The return distributions for the S&P 500 and Nikkei for the next year are given as:


What is the joint distribution matrix if the two return series are unrelated?


选项:

解释:

If the two variables are unrelated, then the joint distribution is just given by the products

fX1,X2(x1,x2)=fX1(x1)fX2(x2)f_{X_1, X_2}(x_1, x_2) = f_{X_1} (x_1)f_{X_2} (x_2)

For example, the probability of seeing -10% on the S&P and -5% on the Nikkei is 25%*20% = 5%.


想问 Nekki的25%是 5%+15%+5%=25% 20%=5%+10%5%


1 个答案

pzqa39 · 2024年03月14日

嗨,从没放弃的小努力你好:



当SP是-10,概率根据题干(上图)是25%;当Nikkei是-5 概率是20%, 25% x 20% =5% 对应下图答案

再举个例子 当SP是-10,概率根据题干是25%,当Nikkei return是0 概率是60%, 25% x 60% =15% ,对应答案中的15%



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努力的时光都是限量版,加油!