IMC 2009
contestants 347 · problems 10 (5+5) · scale 0–10 · per-problem yesDay-1 per-problem scores were partly unreadable in the source.
Per-problem difficulty
Day 1
Day 2
Difficulty vs discrimination
Each dot is one problem. X — how many solved it (scored ≥ 8 of 10); Y — discrimination, i.e. how well the problem told strong contestants from weak ones (score-vs-total correlation).
A good problem sits high and away from the edges. Bottom-left dots separated nobody — almost everyone failed them the same way.
Problem statistics
Same data as the Day 1 / Day 2 charts above. Add diploma cohorts to compare winners against the field.
| # | difficulty | all | disc | topics | ||||
|---|---|---|---|---|---|---|---|---|
| avg | solved | near-0 | ||||||
| Day 1 | ||||||||
| P1 | easy | 9.3 | 88% | 2% | 0.33 | real analysis | ||
| P2 | easy | 6.4 | 61% | 29% | 0.45 | linear algebra | ||
| P3 | hard | 3.5 | 25% | 44% | 0.55 | combinatorics | ||
| P4 | killer | 0.1 | 0% | 98% | 0.22 | complex analysispolynomials | ||
| P5 | killer | 0.5 | 4% | 92% | 0.28 | geometrylinear algebra | ||
| Day 2 | ||||||||
| P6 | easy | 7.1 | 65% | 20% | 0.45 | geometryintegration | ||
| P7 | medium | 4.9 | 39% | 42% | 0.51 | real analysisinequalities | ||
| P8 | hard | 2.5 | 15% | 60% | 0.33 | linear algebra | ||
| P9 | hard | 2.2 | 21% | 76% | 0.46 | group theorypolynomials | ||
| P10 | killer | 0.0 | 0% | 99% | 0.19 | linear algebra | ||
A diploma-cohort cell needs at least 5 scores, else it shows “—”. How these statistics are computed →