The population in this case refers to the entire group that Matthew is interested in studying, which is all the students visiting the stadium. He records a sample of 200 students to estimate information about this broader population.

So, the correct answer is:

All the students visiting the stadium.

Would you like more details or have any questions?

Here are 5 related questions to expand on this:

1. What is the difference between a population and a sample in statistics?
2. How can Matthew ensure that his sample of 200 students is representative of the population?
3. What is a population parameter and how is it different from a sample statistic?
4. What sampling methods could Matthew use to avoid bias in his study?
5. How does the law of large numbers apply to Matthew’s study?

Tip: When collecting a sample, random sampling is crucial to ensure that the sample accurately represents the population.