1. Suppose, on average 2 persons in 400 make a numerical error in preparing his or her income tax return. If 1000 are selected at random and examined, find the probability that 6, 7 or 8 of them contain an error.
2. A high school basketball player is 80% free shooter. What is the probability that during the game he makes his third free throw in the fourth shot? And what is the probability that he makes his first free throw in the fifth shot?