IMC 2018
contestants 349 · 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 | 9.2 | 89% | 6% | 0.29 | sequences & seriesinequalities | ||
| P2 | medium | 4.5 | 40% | 48% | 0.56 | abstract algebragroup theory | ||
| P3 | hard | 2.8 | 19% | 52% | 0.47 | linear algebra | ||
| P4 | hard | 1.7 | 16% | 81% | 0.48 | functional equationsreal analysis | ||
| P5 | killer | 0.5 | 3% | 94% | 0.39 | geometrynumber theory | ||
| Day 2 | ||||||||
| P6 | easy | 8.6 | 81% | 8% | 0.36 | linear algebra | ||
| P7 | medium | 5.2 | 43% | 30% | 0.56 | sequences & series | ||
| P8 | very hard | 1.6 | 6% | 64% | 0.40 | combinatorics | ||
| P9 | very hard | 1.3 | 9% | 80% | 0.52 | polynomials | ||
| P10 | killer | 0.3 | 1% | 96% | 0.37 | number theorysequences & series | ||
A diploma-cohort cell needs at least 5 scores, else it shows “—”. How these statistics are computed →