## The Race

### Problem 232

Published on 13 February 2009 at 05:00 pm [Server Time]

Two players share an unbiased coin and take it in turns to play "The Race". On Player 1's turn, he tosses the coin once: if it comes up Heads, he scores one point; if it comes up Tails, he scores nothing. On Player 2's turn, she chooses a positive integer `T` and tosses the coin `T` times: if it comes up all Heads, she scores 2^{T-1} points; otherwise, she scores nothing. Player 1 goes first. The winner is the first to 100 or more points.

On each turn Player 2 selects the number, `T`, of coin tosses that maximises the probability of her winning.

What is the probability that Player 2 wins?

Give your answer rounded to eight decimal places in the form 0.*abcdefgh* .

Go to back to Problems