[Math] pigeonhole principle clarification

combinatoricspigeonhole-principleprobability

Would the following statement be applicable to the pigeonhole principle? Or can I simply do $100 \times 50 = 5000$?

What is least amount of students in a school to guarantee that there are
at least 100 students from the same state?

Best Answer

Your answer is not quite correct. The most you can have WITHOUT having 100 students from the same state is $50\cdot99=4950$; so, the minimum to guarantee it is $4950+1=4951$.

Although I didn't say 'by the Pigeonhole principle', that's what has happened here.