In a group of 25 people, a person tells a rumor to a second person, who in turns tells it to a third person, and so on. Each person tells the rumor to just one of the people chosen at random, excluding the person from whom he/she heard the rumor. The rumor is told 10 times. What is the probability that the rumor will not be repeated to any one person once more? What is the probability that the rumor will not return to the originator? Use simulation to find the expected value of the number of persons having knowledge of the rumor.