A class with 2N students took a quiz, on which the possible scores were
0, 1, . . . , 10. Each score appeared at least once.
The average score for this class was exactly 7.4.
Show that the class can be divided into two groups of N members each, such that that the average score for each group was exactly 7.4.
Here is a way it could work for a group of 30 students and a subgroup of 15 students:
score N points
0 1 0
1 1 1
2 1 2
3 1 3
4 1 4
5 1 5
6 1 6
7 1 7
8 5 40
9 16 144
10 1 10
7.4 30 222 avg/total
score N points
0 0 0
1 1 1
2 0 0
3 0 0
4 1 4
5 1 5
6 1 6
7 1 7
8 2 16
9 8 72
10 0 0
7.4 15 111 avg/total
Edited on February 24, 2024, 11:50 am
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Posted by Larry
on 2024-02-24 11:49:10 |