The probability of any event ranges from
zero to one. Let’s start with the extremes: zero and one. The probability of zero means that the event has zero chance of happening. It will never occur. An event has probability one if it will
occur for certain. In the middle, a probability of one-half indicates that
the event has 50% chance of happening. In other words, the event is as likely to
occur as it is not to occur. Any probability that is greater than
one-half indicates that the event is more likely to occur that it is not to
occur. And a probability that is below one-half indicates that the event is
more likely not to occur than it is to occur.