问一道题：NO.PZ2015120604000168

问题如下：

You are building models for forecasting earnings per share of two construction companies, A and B. The probability that Company A's EPS will increase at the end of year is 0.45. The probability that Company B's EPS will increase at the end of year is 0.25. The probability that two companies' EPS both increase is 0.10. What is the probability that at least one of the two companies' EPS will increase according the forecasting models?

选项：

0.20

0.40

0.60

解释：

C is correct.

The probability that at least one of the two companies' EPS will increase=0.45+0.25-0.10=0.60

您好，我先用P（A）*P（B）=P（AB）做了初步判断，以为是independence关系，因此发现没有正确答案。这个判断等式，结果需要保留小数点多少才算与P（AB）的数值一致？

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星星_品职助教 · 2020年04月29日

同学你好，

P(A)×P(B)=0.45×0.25=0.1125，并不等于P(AB)=0.10，所以不是独立关系。

这道题并不用刻意的去考虑是否独立，考察的是P(A orB），直接代入公式=P(A)+P(B)-P(AB)即可，三个数都给了。

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NO.PZ2015120604000168问题如下You are builng mols for forecasting earnings per share of two construction companies, A anThe probability thCompany A's EPS will increase the enof yeis 0.45. The probability thCompany B's EPS will increase the enof yeis 0.25. The probability thtwo companies' EPS both increase is 0.10. Whis the probability thleast one of the two companies' EPS will increase accorng the forecasting mols? A.0.20 B.0.40 C.0.60 C is correct.The probability thleast one of the two companies' EPS will increase=0.45+0.25-0.10=0.60P（A）*1-P（B）+P（B）*1-P（B）+P（A B）=0.45*0.75+0.25*0.55+0.1=0.58

2022-03-14 09:36 1 · 回答

想问下这道题目，为什么是减去0.1，而不是加上0.1呢？因为感觉A和B两个同时发生，也是属于至少一个发生的范围里的吧？

2019-12-27 12:35 1 · 回答

这道题的考点是什么？题干的意思我不太明白

2019-10-14 20:02 1 · 回答

为什么要减去0.1了？不是问的2个公司中至少有一个公司EPS会增长的概率吗？不应该是0.45+0.25+0.10吗？

2018-08-29 18:11 1 · 回答

问一道题：NO.PZ2015120604000168

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