(i) If there is absolutely no chance a person will purchase a new car this year, the probability assigned to this event is zero. (ii) If the set of events are collectively exhaustive and mutually exclusive, the sum of the probabilities equals 1. (iii) Suppose four heads did appear face up on the toss of a coin four times. The probability that a head will appear face up in the next toss of the coin is 1/2 or 0.5.