MathCastle
ChallengeMedium

Challenge · Medium problem

You start with $2 and repeatedly bet $1 on a biased coin you win with probability 23\dfrac23 each round (a win gains $1, a loss costs $1). You stop upon reaching $0 or $5. If the expected number of rounds played is mn\dfrac{m}{n} in lowest terms, find m+nm+n.

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