Alex gets an A in ECE 153 and flies home determined to convert as many people as she can into probability lovers, or probabilistic. Every person Alex meets gets a "lecture" about the beauty and utility of the subject and with probability half gets infected with Alex’s love for the topic, and becomes a probabilistic, and with probability half does not. Each person’s response is independent of all others. Let Xn be the random number of probabilists among the first n people Alex meets. For example, X1 is 0 or 1, each with probability 1/2, while X2 is 0, 1, or 2, etc