BEBRAS 2026 Grade 9-10 Round 2 Ext Question 3

Question 3

Maria has 19 plain tiles and 5 flower tiles, shown in the original key.



She tiles a floor of 5 rows and 4 columns, starting at the arrow. She works left to right along each row, then continues left to right on the next row. The result is below.



Which strategy did she use?

1. Place flower tiles so that no two flower tiles are adjacent.
2. Separate plain-tile groups with one flower tile, making each plain group twice as large as the previous group.
3. Ensure that every column has at least one flower tile.
4. Separate plain-tile groups with one flower tile, making each plain group one tile larger than the previous group.