Key learning points

1. The probability of an outcome can be found with a probability tree diagram showing all possible outcomes for two events.
2. The probability of a set of outcomes can be found using a probability tree diagram.
3. The probability of a set of outcomes can be found using a probability tree, even when outcomes are not equally likely.

Keywords

• Outcome - An outcome is a result of a trial (e.g. getting heads when flipping a coin once or getting two heads when flipping a coin twice).

• Event - An event is a subset of a sample space. i.e. An outcome or set of outcomes that may occur from a trial (e.g. flipping a coin twice and getting the same result each time).

• Probability tree - Each branch of a probability tree shows a possible outcome from an event or from a stage of a trial, along with the probability of that outcome happening.

• Sample space - A sample space is all the possible outcomes of a trial. A sample space diagram is a systematic way of producing a sample space.

Common misconception