大于等于3 为什么不是 1-（p小于等于3）而只是小于3

NO.PZ2023091601000029

问题如下：

A multiple choice exam has ten questions, with five choices per question. If you need at least three correct answers to pass the exam, what is the probability that you will pass simply by guessing?

选项：

A.0.8% B.

20.1%

67.8%

32.2%

解释：

The probability of an event is between 0 and 1. If these are mutually exclusive events, the probability of individual occurrences are summed. This probability follows a binomial distribution with a p-parameter of 0.2. The probability of getting at least three questions correct is 1 – [p(0) + p (1) + p (2)] = 32.2%.

大于等于3 为什么不是 1-（p小于等于3）而只是小于3 ？

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1 个答案

pzqa27 · 2024年07月16日

嗨，从没放弃的小努力你好：

这里是1减去对0个题，1个题，和2个题的概率。剩下的就是对3个题，4个题...10个题的概率，这就是大于等于3的通过情况

至于为什么不是 1-（p小于等于3），因为P=3就算通过考试了，所以只能是1减去小于3的情况。

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NO.PZ2023091601000029 问题如下 A multiple choiexhtenquestions, with five choices per question. If you neeleast three correctanswers to pass the exam, whis the probability thyou will pass simply byguessing? A.0.8% B.20.1% C.67.8% 32.2% The probability of anevent is between 0 an1. If these are mutually exclusive events, theprobability of invioccurrences are summe This probability follows abinomistribution with a p-parameter of 0.2. The probability of getting atleast three questions correis 1 – [p(0) + p (1) + p (2)] = 32.2%. 为什么不用二项分布？求解析！

2023-10-14 20:34 1 · 回答

大于等于3 为什么不是 1-（p小于等于3）而只是小于3

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