This states that the probability of the occurrence of two mutually exclusive events is the sum of their individual probabilities. If we consider all possible outcomes of the toss of two coins as shown, there is only one outcome of the four in which both coins have come up heads, so the probability of getting heads on both coins is 0.25. The probability of getting heads on the toss of a coin is 0.5. The Product Rule is evident from the visual representation of all possible outcomes of tossing two coins shown above. The probability of getting two heads on two coin tosses is 0.5 x 0.5 or 0.25.Ī visual representation of the toss of two coins. This states that the probability of the occurrence of two independent events is the product of their individual probabilities. There are two useful rules for calculating the probability of events more complicated than a single coin toss. The two outcomes (heads or tails) are therefore mututally exclusive if the coin comes up heads on a single toss, it cannot come up tails on the same toss. For any individual toss of the coin, the outcome will be either heads or tails. The two outcomes of the toss of a coin are heads or tails.

The probability of heads on the first toss is 50%, just as it is on all subsequent tosses of the coin. When a coin is tossed twice, the coin has no memory of whether it came up heads or tails the first time, so the second toss of the coin is independent.

The probability of an event can also be expressed as a percentage (e.g., an outcome of heads on the toss of a fair coin is 50% likely) or as odds (e.g., the odds of heads on the toss of a fair coin is 1:1).Ī single toss of a coin is an event (also called a trial) that is not connected to or influenced by other events. For example, the probability of an outcome of heads on the toss of a fair coin is ½ or 0.5. The likelihood of an event is expressed as a number between zero (the event will never occur) and one (the event is certain). Probability is a field of mathematics that deals with calculating the likelihood of occurrence of a specific event. You can understand probability by thinking about flipping a coin.

Heads or tails coin flip