Problem

Source: Kosovo MO 2020 Grade 10, Problem 2

Tags: Kosovo, combinatorics, national olympiad, Olympiad



Ana baked 15 pasties. She placed them on a round plate in a circular way: 7 with cabbage, 7 with meat and 1 with cherries in that exact order and put the plate into a microwave. She doesn’t know how the plate has been rotated in the microwave. She wants to eat a pasty with cherries. Is it possible for Ana, by trying no more than three pasties, to find exactly where the pasty with cherries is?