Compound Events

Pre-Algebra · Axiom Academy

When two events combine, one word decides everything: "or" means add, "and" means multiply. A simple event asks about a single outcome — like rolling a 4. A compound event bundles two or more simple events with a connecting word. The animation shades the die faces each one cares about: a simple event lights up one face, the compound event "1 or 6" lights up two . Simple: rolling a 4 on a die — one outcome. Compound (or): rolling a 4 or a 6 — two outcomes joined. Compound (and): flipping heads and rolling a 3 — two events that must both happen. When you want one event OR another, you collect both sets of winning outcomes — so you add the probabilities. The animation lays out all six die faces, then fills the "1" slice and the "6" slice; the shaded amount grows from to as each piece is added. Add the pieces when events can't both happen (mutually exclusive) What is the probability of rolling a 1 OR a 6? and . They can't both happen on one roll, so just add: Sometimes two events can happen at once — a card can be red and a face card. If you just add, you count that shared region twice . The animation shades both groups, then lifts out one copy of the overlap so each card is counted exactly once. Probability of drawing a red card OR a face card from a 52-card deck? , , and (the cards counted twice). 4. The Multiplication Rule (AND)

This is the written version of the interactive lesson above. See the full Pre-Algebra course.