1. "There are two balls in a bag (either black or white). If you draw a white ball, put it back, draw again and it's still a white ball, put it back, what is the probability of drawing a white ball the next time?" 2. "There are 52 playing cards, 26 of which are red and 26 are black. If you draw cards randomly without replacement, gaining +1 for a red card and -1 for a black card, when should you stop to maximize your earnings?"