Probability is the ratio of the total outcomes in an experiment to the number of outcomes that are favorable to the event of which we are finding the probability of. It is important that the event must always be associated to the experiment being talked about. For example: finding the probability of getting a 2 in the experiment of tossing a coin is not possible. The probability of the given event can only be found in the event of throwing a dice. Probability is always lying in the closed interval of 0 and 1, that is, [0, 1]. When then probability is 0 we call the event impossible to happen and when the probability is equal to 1, we call the event to be sure to happen.
There are two types of probabilities we talk about: theoretical and experimental. In theoretical probability we follow the formula as it is as given by the definition of the probability. That is, we divide the number of outcomes that are favorable to the event by the total number of outcomes in order to obtain the event’s probability.