MathDB

14

Part of 2022 Math Prize for Girls Problems

Problems(1)

Math Prize 2022 Problem 14

Source:

10/12/2022
Across the face of a rectangular post-it note, you idly draw lines that are parallel to its edges. Each time you draw a line, there is a 50%50\% chance it'll be in each direction and you never draw over an existing line or the edge of the post-it note. After a few minutes, you notice that you've drawn 20 lines. What is the expected number of rectangles that the post-it note will be partitioned into?