# Pink Lemurs: Classification Metrics: Official Solution

*English translation by SOTA – AI Community of the Russian original. Organisers who would like this translation removed can email sota.ai.community@gmail.com.*

*Task 3 of the school stage (Moscow) of the All-Russian School Olympiad (VsOSh) 2025/26 in artificial intelligence, grades 9–11: official answer and solution (the statement is in a separate file). Original: [sol-ai-9-11-sch-msk-25-26.pdf](https://vos.olimpiada.ru/upload/files/Arhive_tasks/2025-26/school/ai/sol-ai-9-11-sch-msk-25-26.pdf).*

**Correct answer:** $M_1$ — model A; $M_2$ — model B; $M_3$ — model A; $M_4$ — model D; $M_5$ — model C.

**Exact match of the answer — 1 point. Maximum score for the task — 12**

*Translator's note: the original prints this scoring line exactly as above; it does not say how the 12 points are distributed.*

**Solution.**

Let us compute the values.

**Model A** (all — class 0):

$$
M_1 = \tfrac{90}{100} = 0.9, \quad M_2 = 0, \quad M_3 = 1, \quad M_4 = \tfrac{1}{2}, \quad M_5 \text{ is undefined (there are no predictions of 1)}.
$$

**Model B** (all — class 1):

$$
M_1 = \tfrac{10}{100} = 0.1, \quad M_2 = 1, \quad M_3 = 0, \quad M_4 = \tfrac{1}{2}, \quad M_5 = \tfrac{10}{100} = 0.1.
$$

**Model C**:

$$
M_1 = \tfrac{7+82}{100} = 0.89,\ M_2 = \tfrac{7}{10} = 0.7,\ M_3 = \tfrac{82}{90} \approx 0.911,\ M_4 \approx 0.806,\ M_5 = \tfrac{7}{7+8} = \tfrac{7}{15} \approx 0.467.
$$

**Model D**:

$$
M_1 = \tfrac{8+76}{100} = 0.84,\ M_2 = \tfrac{8}{10} = 0.8,\ M_3 = \tfrac{76}{90} \approx 0.844,\ M_4 \approx 0.822,\ M_5 = \tfrac{8}{8+14} = \tfrac{8}{22} \approx 0.364.
$$

Comparing, we obtain the maxima: $M_1$ and $M_3$ — for model A, $M_2$ — for B, $M_4$ — for D, $M_5$ — for C.