MathDB

8

Part of 2008 Korea Junior Math Olympiad

Problems(1)

small groups created by 12 members in a club

Source: KJMO 2008 p8

5/2/2019
There are 1212 members in a club. The members created some small groups, which satisfy the following: - The small group consists of 33 or 44 people. - Also, for two arbitrary members, there exists exactly one small group that has both members. Prove that all members are in the same number of small groups.
combinatoricsSets