1. The corresponding percentage of three people who make three sentences is 25%, so the total number of people who speak is 3/25%= 12, and those who make four sentences are 12-3- 1 = 4 people … on average (2 * 65438+.

2. There are two men and one woman who send three words, and three women and one man who send four words. The tree diagram is to draw three forks first, male, male and female. After that, each fork has four small forks, female, male. One * * * is 12 cases, of which 7 cases happen to be a man and a woman, and the probability is 7/ 12.