Because the question is "at least" how many students will take part, and each student will take part in at least one event, and there is no rule that everyone can only take part in several events at most, so we can directly find out how many boys and girls will take part in the sports meeting. I saw that the number of boys participating in the four events was 5, 10, 2 and 3 respectively. Because of the least consideration, it is repeated to the greatest extent, which means that some boys can participate in multiple events by themselves, so at least 10 boys participated in the sports meeting. Similarly, at least 10 girls participated in the sports meeting. Therefore, at least 20 students took part in the sports meeting.