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CC · 2023年09月02日

可以画图解答一下吗?

NO.PZ2022062760000001

问题如下:

An analyst is examining a portfolio that consists of 2,500 subprime mortgages and 800 prime mortgages. Of the subprime mortgages, 500 are late on their payments. Of the prime mortgages, 64 are late on their payments. If the analyst randomly selects a mortgage from the portfolio and it is currently late on its payments, what is the probability that it is a subprime mortgage?

选项:

A.

60%

B.

67%

C.

75%

D.

89%

解释:

中文解析:

求条件概率:

P(Mortgage is late) = (500+64)/(2500+800) = 17.1%

P(Subprime mortgage and late) = 500/3300 = 15.2%

P(Subprime mortgage | Mortgage is late) = P(Subprime mortgage and late)/P(Mortgage is late) = 15.2% / 17.1% = 0.89 = 89%

In order to solve this conditional probability question, first calculate the probability that any one mortgage in the portfolio is late.

This is: P(Mortgage is late) = (500+64)/(2500+800) = 17.1%.

Next, use the conditional probability relationship as follows: P(Subprime mortgage | Mortgage is late) = P(Subprime mortgage and late)/P(Mortgage is late).

Since P(Subprime mortgage and late) = 500/3300 = 15.2%, then

P(Subprime mortgage | Mortgage is late) = 15.2% / 17.1% = 0.89 = 89%.

Hence the probability that a random late mortgage selected from this portfolio turns out to be subprime is 89%.

图中标注比例还是直接带入数字会方便一点?

2 个答案

DD仔_品职助教 · 2023年09月06日

嗨,爱思考的PZer你好:


具体请看下图:

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就算太阳没有迎着我们而来,我们正在朝着它而去,加油!

DD仔_品职助教 · 2023年09月02日

嗨,努力学习的PZer你好:


同学你好,

具体请看下图

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虽然现在很辛苦,但努力过的感觉真的很好,加油!

CC · 2023年09月06日

老师再问下,您这个图很清晰了,就这个题可以用二叉树(贝叶斯公式)来做吗?可以的话二叉树的画图计算可以出一个吗?