The document discusses experimental and theoretical probability. Experimental probability is determined by repeated testing and observing results, calculated as the number of times an event occurred divided by the total number of tests. Theoretical probability is calculated under ideal circumstances based on possible outcomes. For a family with 3 children, the theoretical probability of having 2 girls can be calculated as the number of ways to have 2 girls (3 combinations) divided by the total possible outcomes (8 combinations). An example is also given of simulating a binomial experiment using a calculator to determine the probability of getting exactly 2 heads when flipping 3 coins 40 times.