Probability is defined as the extent to which an event is likely to occur. It is measured as a number of favorable events to occur from the total number of event that occurs. It is to be noted that the probability of an event is always 0 ≤ Pe ≤ 1.
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Conditional Probability is the likelihood of an event or outcome occurring based on the occurrence of a previous event or outcome. It simply depends on any event in the past which has already taken place.
If E and F are two events with the same sample space of a random experiment, then the conditional probability of the event E gives that F has occurred, i.e. P(E|F) is,
P(E|F) = P(E ∩ F)/P(F), provided P(F) ≠ 0