In a soccer tournament, each team plays each other team exactly once. The tournament adopts a scoring system in which a win counts
3
points, a draw counts
1
point, and a loss counts as
0
points. After the tournament, there is a team which has both earned the most total points and won the fewest games. Find the smallest number of teams in the tournament for which this is possible
Question:
In a soccer tournament, each team plays each other team exactly once. The tournament adopts a scoring system in which a win counts
3
points, a draw counts
1
point, and a loss counts as
0
points. After the tournament, there is a team which has both earned the most total points and won the fewest games. Find the smallest number of teams in the tournament for which this is possible
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Asked by: Test User 100263
Created at: 2025-05-18 10:05:32
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Let’s analyze the problem step by step:
**Restatement:**
- There are \( n \) teams.
- Each team plays every other team **once**: \(\binom{n}{2}\) matches.
- Win: 3 points, Draw: 1 point, Loss: 0 points.
- After the tournament, **some team has:**
- **the most points**
- **but has won the fewest games** (among all teams).
We are to find the **smallest \( n \)** for which this is possible.
---
### 1. **Understanding the Requirement**
- "Most points, fewest wins": the team with the highest points must have the lowest number of wins of all teams.
If a team has the most points but the fewest wins, it must have earned many points from draws (since a win is worth more, but they have fewer wins).
---
### 2. **Let’s Try Small Values of \( n \)**
#### **Case \( n = 2 \):**
- Only one match.
- Impossible: the winner of the match has most points and most wins.
#### **Case \( n = 3 \):**
- 3 teams: A, B, C.
- Matches: AB, AC, BC.
Suppose one team has fewest wins but most points. But a win is 3 points; if you have fewest wins, you must get most points from draws. Try all draws: all teams have 2 points.
- No possibility.
#### **Case \( n = 4 \):**
- Teams: A, B, C, D.
- Each plays 3 matches.
Suppose team A has 0 wins, but the most points. All draws: each team earns 3 points (not unique).
Suppose A has 1 win: then others must have at least 1 win as well (since there are 6 matches, 6 wins in total). Try to distribute more draws to A, but the other teams will have at least as many wins.
**Conclusion:** For \( n = 2, 3, 4 \), **not possible.**
---
### 3. **Try \( n = 5 \)**
- 5 teams: A, B, C, D, E.
- Each plays 4 matches.
Suppose team A has **0 wins** and gets only draws: 4 points.
If any team wins at least one match, it gets at least 3 points (for one win, more if it draws others).
But other teams will also have at least as many points (since A only draws, the points are distributed).
Let’s try to see if there's a way for a team with fewer wins (maybe 1) to have more points than all others.
Let's try to **construct a scenario:**
Suppose Team A: 1 win, 3 draws: \(1 \cdot 3 + 3 \cdot 1 = 6\) points.
Other teams: Let's see if they can have at least 2 wins (since A has the fewest, and only 1), but get less than 6 points.
But 2 wins alone is 6 points already, and possibly more with draws.
So for \(n=5\), it *still seems impossible*.
---
### 4. **Try \( n = 6 \)**
- 6 teams: Each plays 5 matches.
Suppose Team A has **all draws:** 5 points.
Suppose Team A has 1 win, 4 draws: 3 + 4 = 7 points.
Can we arrange for other teams to have at least 2 wins, but fewer points than Team A?
Suppose Team B: 2 wins (6 points), 3 losses (0 points): 6 points.
So now, Team A (with 1 win) has 7 points, Team B (with 2 wins) has 6 points.
Is it possible for every other team to have at least 2 wins, but fewer points than A?
Let’s check the *total number of wins* in the tournament.
Total number of matches: \( \binom{6}{2} = 15 \) matches.
Each match is either a win/loss or draw.
Let’s say Team A: 1 win, 4 draws = 7 points.
The other 5 teams: Each plays 5 matches (one against A, 4 against others).
For A's results:
- 1 win (vs B)
- 4 draws (vs C, D, E, F)
So:
- B loses to A (0 points), plays C, D, E, F.
- C, D, E, F all drew with A.
Let’s try to assign two wins to each of the other teams, but arrange so that their points are less than 7.
But as before, 2 wins = 6 points, even with 3 losses, that's 6 points.
But if a team has 3 wins, it's 9 points.
So **Yes, it is possible for a team with 1 win (A) to have more points than teams with more wins (if those wins are not accompanied by draws).**
But the key condition is **A has the most points and the fewest wins.**
Let's try to construct an explicit example for 6 teams.
---
### 5. **Explicit Construction for \( n = 7 \)**
Let's generalize:
Suppose:
- Team A draws all its matches: 6 draws, 6 points.
- Other teams beat each other in a cycle (e.g., B beats C, C beats D, ..., G beats B), and lose/draw with A.
Let’s try:
- A draws all matches: 6 points, 0 wins.
- B: loses to A (draw), beats C, loses to D, loses to E, loses to F, loses to G. (1 win, 1 draw, 4 losses): 4 points.
- C: loses to A (draw), loses to B, beats D, loses to E, loses to F, loses to G. (1 win, 1 draw, 4 losses): 4 points.
- D: loses to A (draw), loses to B, loses to C, beats E, loses to F, loses to G. (1 win, 1 draw, 4 losses): 4 points.
- E: loses to A (draw), loses to B, loses to C, loses to D, beats F, loses to G. (1 win, 1 draw, 4 losses): 4 points.
- F: loses to A (draw), loses to B, loses to C, loses to D, loses to E, beats G. (1 win, 1 draw, 4 losses): 4 points.
- G: loses to A (draw), beats B, loses to C, loses to D, loses to E, loses to F. (1 win, 1 draw, 4 losses): 4 points.
But the sums do not add up: with 7 teams, each playing 6 matches, total matches is 21; total points is at most 3 * 21 = 63, but with many draws, less.
But the key is with more teams, the more draws A can have, and the more likely A can be the unique highest scorer with only draws.
The **classic construction** is for \( n = 7 \):
Let’s try:
- Team A draws all matches: 6 points, 0 wins.
- All other matches are played as wins/losses (no draws), with each of B, C, D, E, F, G winning exactly one game among themselves:
- B beats C
- C beats D
- D beats E
- E beats F
- F beats G
- G beats B
Each of B–G: 1 win (3 points), 0 draws, 5 losses (0 points): 3 points.
Each also drew with A: 1 point extra, so each has **4 points**.
So A: 0 wins, 6 draws = **6 points**
Everyone else: 1 win, 1 draw, 4 losses = **4 points**
A has the **most points (6)** and **fewest wins (0)**.
#### **Check for \( n = 6 \):**
Try the same construction:
- A draws all matches: 5 points, 0 wins.
- B beats C, C beats D, D beats E, E beats B. F? Can't form a cycle.
Actually, with 5 teams (aside from A), you can't form a perfect cycle.
So, **n = 7 is the smallest number for which this construction works.**
---
## **Final Answer**
\[
\boxed{7}
\]
is the **smallest number of teams** in the tournament for which it is possible for a team to have the most points and the fewest wins.
**Construction:**
- Team A draws every match: 0 wins, 6 draws, 6 points.
- Every other team beats one and loses to 4, with 1 draw (against A): 1 win, 1 draw, 4 losses = 4 points.
- Thus, A has the most points and the fewest wins.
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