1) Calculate the mean value for the number of heads appearing in a simulations throw of 3 coins.
2) Suppose your neighbour has two children and you come to know that one of his children is a son. What is the probability that his other child is a son.
3) Assume that on a weekday one telephone number out of ever ten being called is busy. If 6 randomly selected numbers are called what is the probability that at least three of them will be busy.
4) If power failures occur according to a poisson distribution with an average of 3 failures every 20 weeks, calculate the probability that there will not be more than one failure during a particular week.