MathDB

Andy and Eddie play a game in which they continuously flip a fair coin. They stop flipping when either they flip tails, heads, and tails consecutively in that order, or they flip three tails in a row. Then, if there has been an odd number of flips, Andy wins, and otherwise Eddie wins. Given that the probability that Andy wins is

\frac{m}{n}

, where

m

and

n

are relatively prime positive integers, find

m+n

.
Proposed by Anderw Zhao and Zachary Perry

A15 B20

Problems(1)