Two darts players throw altemately at a board and the first to score a bull wins. On each of their throws player A has probability Pa and player B Pg of success; the results of different throws are...

Extracted text: Two darts players throw altemately at a board and the first to score a bull wins. On each of their throws player A has probability Pa and player B Pg of success; the results of different throws are independent. If A starts, calculate the probability that he/she wins.