olymmath

AIME 2019b Problem 2

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Lilypads 1,2,3,…1,2,3,\ldots lie in a row on a pond. A frog makes a sequence of jumps starting on pad 11. From any pad kk the frog jumps to either pad k+1k+1 or pad k+2k+2 chosen randomly with probability 12\tfrac{1}{2} and independently of other jumps. The probability that the frog visits pad 77 is pq\tfrac{p}{q}, where pp and qq are relatively prime positive integers. Find p+qp+q.

Dataset text AIME 1983 to 2026. Quoted with source.

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