Checklist VsOSh AI 2026 School Stage (Sirius platform, region group 3), grades 9–11 · Task 2
The Flower-Shop Intern
Russian title: Задание 2
Compute the expected number of correct orders before the first order that breaks an "always roses" strategy.
The task
Customers of a flower delivery service order roses with probability 2/3 and daisies with probability 1/3. Having seen six orders (roses, roses, daisies, roses, roses, roses), the intern Petya decides to send only roses; orders arrive one after another until the first daisy order, after which he is fired.
Find the expected number of bouquets he makes correctly today.
Abridged and translated by SOTA from the official Russian materials. The official statement has the exact rules, and it wins wherever this summary differs.
In English
This task was published in Russian. SOTA translated its 3 files into English on 16 September 2026.
- Task statement Russian original of Task statement
- Official solution Russian original of Official solution
- Full paper with solutions (all tasks of the tour) Russian original of Full paper with solutions (all tasks of the tour)
Read the task statement in English
The Flower-Shop Intern
English translation by SOTA – AI Community of the Russian original. Organisers who would like this translation removed can email [email protected].
Task 2 of the school stage of the All-Russian School Olympiad (VsOSh) 2025/26 in artificial intelligence (region group III), grades 9–11. The official answer and solution are in a separate file.
Customers of the flower delivery service “Monobouquet” order bouquets of roses with probability and bouquets of daisies with probability . Yesterday the intern Petya carefully looked through the orders and sent out six bouquets: roses, roses, daisies, roses, roses, roses. After that, he decided not to waste time reading the descriptions, but to make all bouquets from roses only and send them straight to the customer's address. Today orders arrive one after another until a request for daisies appears; after that Petya will be fired, because the customer will receive the wrong bouquet! Find the mathematical expectation of the number of bouquets that Petya will manage to make correctly today.
Scoring criterion: 6 points for each correct answer. Total — 12 points
Maximum score for the task — 12
Translated by SOTA. The Russian original is the official version and wins wherever the two differ. Statement and official solution come from one PDF, the analysis of the school-stage tasks for region group III, grades 9–11, linked from the olympiad's Sirius page. If you organise this olympiad and would like the translation removed, email [email protected] and we will take it down.
At a glance
- You get
- Statement only.
- You submit
- One number.
- Scoring
- Exact answer; 12 points (the PDF describes the criterion as "6 points per correct answer, 12 in total").
- Format
- School stage on the Sirius.Courses platform, region group 3, 20 October 2025; grades 9–11; individual; 150 minutes; maximum 112 points for the paper (tasks 1–6: 12 points each; tasks 7–8: 20 points each).