Analysis of test questions: (1) According to the meaning of the question, list all possible situations of the basic event of selecting people in the first group and selecting people in the second group. It can be known that there are 30 cases of selecting people as boys and 3 cases of selecting people as boys, so the probability of selecting people as boys is 0;

(2) Find out that there are boys and girls in 30 basic events and get 25 basic events, so as to calculate the probability of boys and girls in the selected crowd.

Test analysis: (1) I remember that the first group of four people were: the second group of five people took the test 1 respectively.

Let the basic event space consisting of "choose people from the first group and choose people from the second group" be, then

* * * There are 30 kinds of 4 points.

Assuming that "all the selected people are boys" is an event, then event A contains three basic events. 6 points

So the probability that the selected person is a boy is 8 points.

(2) Let "three selected people are boys and girls" as event B, then event B contains 25 basic events. 10 point

So the probability that there are boys and girls among the selected people is ...? 12 point