There are 3 different urns of 12 balls with 4 white balls in each urn. three players—a, b, and c—successively draw from their respective urns, a first, then b, then c, then a, and so on. the winner is the first one to draw a white ball. find the probability of winning for each player if 1. each ball is replaced after it is drawn; 2. the balls that are withdrawn are not replaced.