2019 AMC 8 Problem 19

Below is the video solution and professionally curated solution for Problem 19 of the 2019 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2019 AMC 8 solutions, or check the answer key.

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Concepts:optimizationextremal argument

Difficulty rating: 1610

19.

In a tournament there are six teams that play each other twice. A team earns 33 points for a win, 11 point for a draw, and 00 points for a loss. After all the games have been played it turns out that the top three teams earned the same number of total points. What is the greatest possible number of total points for each of the top three teams?

2222

2323

2424

2626

3030

Video solution:
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Written solution:

We can assume that the top 33 teams won every game against every team not amongst themselves.

They play 32=63 \cdot 2 = 6 games in total, getting a total of 63=186 \cdot 3 = 18 points.

Now, among the top 3,3, each pair of teams plays twice. To even out the scores, we can let one team win one game and let the other team win the other game.

To make the three scores equal while keeping all possible points, split the two games in each pair so each team gets 33 points from that pair. There are 33 such pairs, with each team appearing in 22 pairs.

This means that each team will get an extra 32=63 \cdot 2 = 6 points. Therefore, their maximum score is 18+6=24.18 + 6 = 24.

Thus, the correct answer is C.

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