Theoretical probability is a branch of mathematics that calculates the likelihood of an event occurring based on all possible outcomes. It is determined by dividing the number of favorable outcomes by the total number of possible outcomes. For example, when flipping a fair coin, there are two possible outcomes: heads or tails. The theoretical probability of getting heads is 1 out of 2, or 50%. This concept is often used in various fields, including statistics and game theory, to predict outcomes in situations where randomness is involved. Theoretical probability assumes that all outcomes are equally likely, making it a useful tool for understanding chance in everyday scenarios.