1. **State the problem:** There are 55 musicians playing pieces on oboe, double bass, or trombone. Each piece is either in a major or minor key.
2. **Given data:**
- Total musicians: 55
- Pieces in minor key: $\frac{3}{5} \times 55 = 33$
- Pieces in major key: $55 - 33 = 22$
- Double bass players: 7
- Oboe major pieces: 1
- Double bass minor pieces: 2
- Trombone total players: 29 (given)
3. **Find missing values:**
- Total minor pieces = 33
- Minor pieces on oboe and trombone: $33 - 2 = 31$
- Trombone minor pieces: Let it be $x$
- Oboe minor pieces: $31 - x$
4. **Total players per instrument:**
- Oboe total = major + minor = $1 + (31 - x) = 32 - x$
- Double bass total = major + minor = $m + 2 = 7$ so major on double bass $m = 5$
- Trombone total = major + minor = $t + x = 29$
5. **Total major pieces = 22:**
- Major on oboe = 1
- Major on double bass = 5
- Major on trombone = $t$
So, $1 + 5 + t = 22 \Rightarrow t = 16$
6. **Trombone minor pieces:**
- $t + x = 29 \Rightarrow 16 + x = 29 \Rightarrow x = 13$
7. **Oboe minor pieces:**
- $31 - x = 31 - 13 = 18$
8. **Summary:**
| Instrument | Major | Minor | Total |
|-------------|-------|-------|-------|
| Oboe | 1 | 18 | 19 |
| Double bass | 5 | 2 | 7 |
| Trombone | 16 | 13 | 29 |
9. **Find largest proportion of major pieces:**
- Oboe: $\frac{1}{19}$
- Double bass: $\frac{5}{7}$
- Trombone: $\frac{16}{29}$
10. **Compare fractions:**
- $\frac{5}{7} \approx 0.714$
- $\frac{16}{29} \approx 0.552$
- $\frac{1}{19} \approx 0.053$
Largest proportion is for double bass.
11. **Simplify fraction for double bass:** $\frac{5}{7}$ is already in simplest form.
**Final answer:** The double bass has the largest proportion of pieces played in a major key, which is $\frac{5}{7}$.
Frequency Tree
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