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MathNet 2015-part-07 — 185 problems (EN–VI) Question 165

Math Olympiad Vault · MathNet 2015-part-07 — 185 problems (EN–VI)

Question 165

Consider an $8 \times 8$ grid of squares. A rook is placed in the lower left corner, and every minute it moves to a square in the same row or column with equal probability (the rook must move; i.e. it cannot stay in the same square). What is the expected number of minutes until the rook reaches the upper right corner?