Yr 9 Probability Vocabulary

Vocabulary flashcards defining key probability, statistics, and data representation terms from the Year 9 Probability workbook.

Probability

A measure of the chance of an event happening, which must be between $0$ and $1$ inclusive and can be written as a decimal, fraction, or percentage.

Outcome

One possible result of an experiment.

Event

Something which has a number of outcomes.

Sample Space

A list of all the possible outcomes of an experiment.

Trial

A single run through of an experiment.

Frequency

The number of times an event occurs.

Relative Frequency

The calculated ratio $\text{Relative Frequency} = \frac{\text{Frequency of outcome}}{\text{Total number of outcomes}}$.

Equally Likely

Outcomes that have the same chance of occurring.

Independent Events

Events that do not affect or are not affected by another event.

Theoretical Probability

Probability calculated using the formula $\text{P(event)} = \frac{\text{number of ways it can happen}}{\text{total number of outcomes}}$.

Mutually Exclusive Events

Events that cannot occur together.

Law of Large Numbers

The principle stating that as the number of trials increases, experimental probability approaches theoretical probability.

Long Run Frequency

The estimated probability calculated from simulations or experiments, which becomes more accurate and stable as the number of trials increases.

Discrete Data

Count data that has values that are whole numbers.

Continuous Data

Measurements that can have any value in a given range.

Mean

The average of a set of scores.

Median

The middle value when scores are arranged in order of size in ascending or descending order.

Mode

The score or outcome that occurs the most.

Range

The difference between the highest and the lowest scores.

Variable

Any quantity that varies.

Tally

Recording a mark when a specific outcome occurs in a dataset.

Tree Diagram

A diagram broken into layers matching sequential events, used to systematically list all outcomes and calculate probabilities by multiplying along branches.

Two-Way Table

A table display used to organize categorical data when there are two categorical variables.

Conditional Probability

An event that consists of the occurrence of one event based on the knowledge that another event has already occurred, calculated as $P(A|B) = \frac{P(A \text{ and } B)}{P(B)}$.