Maths Olympiad Prep

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, 2019

Geometry Difficulty 4.9 AIME Prove it United States

Problem:

Dylan has a 100×100100 \times 100 square, and wants to cut it into pieces of area at least 11. Each cut must be a straight line (not a line segment) and must intersect the interior of the square. What is the largest number of cuts he can make?

Solution

Solution:

Since each piece has area at least 11 and the original square has area 1000010000, Dylan can end up with at most 1000010000 pieces. There is initially 11 piece, so the number of pieces can increase by at most 99999999. Each cut increases the number of pieces by at least 11, so Dylan can make at most 99999999 cuts. Notice that this is achievable if Dylan makes 99999999 vertical cuts spaced at increments of 1100\frac{1}{100} units.

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Source: MathNet, licensed CC-BY-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.