NO.PZ2019040801000073
问题如下：
Robin Hill is taking a difficult multiple choice exam. There are 5 questions in the exam and each question has four choices. The choices are almost the same in each question. which of the following amouts is closest to the probability that he will get more than 3 questions correct by randomly guessing ?
选项：
A.3.0%.
B.8.79%.
C.1.56%.
D.25.0%.
解释：
C is correct.
考点：二项分布概率计算
解析：二项分布中答对一题概率是25%，5道题，
正确4道，5道的可能性分别是：
P(4) = 5 x (0.25)4 x (0.75)1= 0.0146484
P(5） = 1x (0.25)5x (0.75)0 = 0.0009766
0.01464 + 0.00098 = 1.562%
有时候是在分不清什么时候用这个伯努利分布，什么时候用泊松分布，请问是看到possion distribution才使用泊松分布，其余的都用伯努利分布的计算公式吗？
