In a sample of 2016 U.S. adults, 242 said Richard Nixon was the worst president since World War II. Three U.S. adults are selected at random without replacement. (Adapted from Harris Interactive) (a) Find the probability that all three adults say Richard Nixon was the worst president since World War II. (b) Find the probability that none of the three adults say Richard Nixon was the worst president since World War II. (c) Find the probability that at most two of the three adults say Richard Nixon was the worst president since World War II. (d) Which of the events can be considered unusual? Explain.