Question: You have Xs and Os (nine of each) in a bag near a tic-tac-toe board. You arbitrarily select an X or an O, and then you place it arbitrarily on the board. Shake the bag, and again arbitrarily select an X or an O and place it arbitrarily on the board (in an open spot).
(a) Consider the event in which you select the same letter twice; define a random variable corresponding to this event and compute its expected value.
(b) What is the probability that both letters are placed in the same row?