# From Precision to Accuracy: 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 5 of the school stage of the All-Russian School Olympiad (VsOSh) 2025/26 in artificial intelligence (region group IV), grades 9–11. Answer and official solution.*

**Answer:** [0.75; 0.75]

**Solution.**

From $\text{Precision} = \dfrac{TP}{TP + FP} = 0.5$ it follows that $TP = FP$ (the denominator is $> 0$).<br>
Since there are $P = 200$ positives, $0 < TP \le 200$. Then

$$TN = 600 - FP = 600 - TP, \qquad \text{Accuracy} = \frac{TP + TN}{800} = \frac{TP + 600 - TP}{800} = \frac{600}{800} = 0.75.$$

Accuracy does not depend on the particular $TP$ (for $0 < TP \le 200$), so the range is the single point $[0.75; 0.75]$.