# Probability Threshold: 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 6 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:** 61

**Solution.**

*Translator's note: the original writes the formulas below for the Russian-language version of Excel (Russian function names, a decimal comma and semicolons between arguments); here they are given with the English function names IF and SUM.*

**Solution in the Russian-language version of Excel.** Suppose that in the table column A holds the probability $p$ and column B the correct label $y$; the data are in rows 2–101.

**Step 1. Compute the prediction by the rule.** In cell C2:

`=IF(A2>=0.6, 1, 0)`

Drag down to C101.

**Step 2. Check whether the prediction matches the true label.** In cell D2:

`=IF(C2=B2, 1, 0)`

Drag down to D101.

**Step 3. Counting the matches.** In any free cell, for example E2:

`=SUM(D2:D101)`

This is exactly the number of rows where $\hat{y} = y$.