Marginal probability refers to the likelihood of a single event occurring without considering any other events. It is calculated by summing the probabilities of all possible outcomes that include the event of interest. For example, if you want to find the marginal probability of rolling a 3 on a six-sided die, you would look at the probability of rolling a 3 regardless of the other numbers. In a probability distribution, marginal probabilities help in understanding the overall behavior of a random variable. They are often represented in tables or graphs, making it easier to visualize the chances of different outcomes. This concept is essential in fields like statistics and data analysis.