MathDB

9

Part of 1987 National High School Mathematics League

Problems(1)

An Interesting Activity

Source: 1987 National High School Mathematics League, Exam One, Problem 9

2/24/2020
Five sets of brothers and sisters attend an activity of kk groups, stipulate that: (1)Anyone cannot be in the same group with his/her sister/brother. (2)Anyone has been in the same group with any other people who is not his/her sister/brother. (3)Only one person has attended moe than one group. Then, the minimun value of kk is________.