A Mean Below Five
Difficulty: Medium · Topics: Discrete Mathematics, Sets, Subsets
A=\1,2,3,4,5,6,7,8,9\
In how many of the two-element subsets of A is the arithmetic mean of the numbers smaller than 5?
Difficulty: Medium · Topics: Discrete Mathematics, Sets, Subsets
A=\1,2,3,4,5,6,7,8,9\
In how many of the two-element subsets of A is the arithmetic mean of the numbers smaller than 5?