Compound Probability for Kids: Two Events, Tree Diagrams and Multiplying (Grade 7 Math)

Hi, I'm Luna from DoodleBeez. Today we are learning about compound probability. A compound event is made of two or more events together, like flipping a coin and rolling a number cube.

Let's list every possible outcome. The coin can land on heads or tails. The cube can show one to six. Two times six gives twelve outcomes. This full list is called the sample space.

What is the chance of heads and a six? Only one of the twelve outcomes works, heads six. So the probability is one twelfth. We can also multiply. One half times one sixth is one twelfth.

A tree diagram helps too. Flip two coins. The first coin branches into heads or tails, and each of those branches again. There are four outcomes, so the chance of two heads is one quarter.

Sometimes we want at least one. With two coins, the outcomes with at least one head are heads heads, heads tails, and tails heads. That is three out of four, so the probability is three quarters.

When one event does not change the other, we call them independent, and we can multiply. A spinner has four equal colors. The chance of red and tails is one quarter times one half, which is one eighth.

Now it's your turn. Roll two number cubes. What is the probability that both show six? Pause and try. Multiply one sixth times one sixth. The answer is one thirty sixth.

Great job! Remember, list the sample space or draw a tree diagram to see every outcome. For independent events, multiply the probabilities. Practice compound probability in Middle School Math at doodlebeez.com. See you next time!