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Equal averages (Posted on 2024-02-24) Difficulty: 2 of 5
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.

No Solution Yet Submitted by Ady TZIDON    
Rating: 3.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Some Thoughts An example, not a proof | Comment 2 of 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
  Posted by Larry on 2024-02-24 11:49:10

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