If i toss 3 pieces on a tic-tac-toe board at random, and I pay you $9 if the pieces create tic-tac-toe, and you pay me $1 if they dont, do you want to play the game? (Expected value problem)

You know there are 2 boys and an unknown number of girls in a nursery at a hospital. Then a woman gives birth a baby, but you dont know its gender, and it is placed in the nursery. Then a nurse comes in a picks up a baby and it is a boy. Given that the nurse picks up a boy, what is the probability that the woman gave birth to a boy? (Hint, it does not matter how many girls are in the nursery to begin with)