How to Calculate Compound Probability With and Without Replacement

Miacademy & MiaPrep Learning Channel

This educational video provides a clear and structured introduction to compound probability, specifically focusing on the "multiplication rule" for calculating the likelihood of two events occurring together. Host Justin uses visual aids and step-by-step examples to explain the critical difference between events that happen "with replacement" versus "without replacement." The video breaks down the mathematical formula P(A and B) = P(A) * P(B|A), making the abstract notation accessible through concrete examples involving bags of marbles and baskets of bagels. The content explores three distinct scenarios: calculating probability without replacement (dependent events), calculating with replacement (independent events), and a real-world word problem involving bagels. Through these examples, the video demonstrates how the sample space—the denominator in the probability fraction—changes when an item is removed and not returned, a common stumbling block for students learning probability statistics. Visual animations of marbles leaving and returning to a jar help students mentally model these changes. This video is an excellent resource for middle and high school math classrooms introducing statistics and probability standards. It serves as a perfect direct instruction tool for distinguishing between independent and dependent events. Teachers can use the built-in pause points to allow students to calculate answers on their own before seeing the solution, making it an interactive component of a lesson on compound events or a review tool for standardized test preparation.