Probability Of Combined Events

Most interesting probability questions involve more than one thing happening: two dice rolled together, two coins tossed, a counter drawn then another. To handle these combined events we need organised ways of listing every possibility, and two simple rules for combining probabilities. Get organised and even busy-looking questions become straightforward.

In this lesson you will list outcomes with sample space tables, picture overlapping events, and follow the branches of a tree to combine probabilities. The two rules at the heart of it are short and memorable: multiply along the branches for AND, add the separate cases for OR. With these tools you can find the chance of almost any combined event.