7 courses for students (1997 Chile NMO P7)
Source:
November 23, 2021
combinatorics
Problem Statement
In a career in mathematics, courses are taught, among which students can choose the ones you want. Determine the number of students in the career, knowing that:
No two students have chosen the same courses.
Any two students have at least one course in common.
If the race had one more student, it would not be possible to do both.