20 14 college entrance examination mathematics Tianjin volume, probability and distribution list questions, only solve the second question! Why did I do something wrong? Why is it superlogarithmic distribution? number The topic of binomial distribution should be like this. If three students are selected, the probability that each student is a girl is 1/2, which are independent of each other. Finding the distribution of the number of girls is a binomial distribution.

This question is not like this. The gender of each student is known and the number of students is limited. They are not independent of each other, so they are not binomial distribution.