For example, assume we wish to determine the probability of drawing a king and/or a queen out of a deck of cards on only one draw. Using the addition rule for probabilities, we get the following: P(King) = 4/52, P(Queen) = 4/52, and P(King and Queen) = 0.
Since it is impossible to draw both a king and queen on the same draw, we can conclude that the probability of drawing either a king or queen from a deck of cards is 8/52, or about 15.4%.