A tree diagram shows all the possible outcomes of an event and their probabilities
A Real Example of a Tree Diagram
It is easier to understand a tree diagram with an example.
Tossing a Coin
If a coin is tossed, the coin can land on Heads
Each outcome has its own branch. There is a branch for Heads and for Tails.
The probability of each outcome is written by each branch. The probability of Heads (1⁄2) is written by the branch. The probability of Tails (1⁄2) is written by the branch.
The probabilities across the branches add
up to 1. They are mutually exclusive and exhaustive events
Another Real Example of a Tree Diagram
A tree diagram can be extended to more than one event.
The tree diagram below is for two coin tosses.
What Is Probability?
A probability is a measure of how likely (how probable
) an event is to happen.
A probability is expressed as a number between 0 (impossible) and 1 (certain).
The formula for finding a probability is shown below: