IMC 2019
contestants 360 · problems 10 (5+5) · scale 0–10 · per-problem yesPer-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 | 6.9 | 54% | 16% | 0.47 | sequences & series | ||
| P2 | medium | 6.1 | 44% | 13% | 0.38 | linear algebranumber theory | ||
| P3 | medium | 5.3 | 41% | 27% | 0.48 | integrationinequalities | ||
| P4 | killer | 0.4 | 2% | 92% | 0.33 | sequences & seriesnumber theory | ||
| P5 | killer | 0.8 | 5% | 91% | 0.35 | linear algebranumber theory | ||
| Day 2 | ||||||||
| P6 | medium | 6.1 | 43% | 2% | 0.46 | real analysis | ||
| P7 | easy | 7.8 | 73% | 15% | 0.43 | sequences & seriesnumber theory | ||
| P8 | very hard | 0.8 | 7% | 91% | 0.38 | combinatorics | ||
| P9 | hard | 2.7 | 20% | 62% | 0.60 | linear algebra | ||
| P10 | killer | 0.6 | 2% | 89% | 0.36 | probabilitygeometry | ||
A diploma-cohort cell needs at least 5 scores, else it shows “—”. How these statistics are computed →