Maths (school) · Part 08
Probability and statistics
Chance, tree diagrams, averages and scatter graphs.
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- Probability scaleA number from 0 to 1 showing how likely something is. 0 means impossible, 1 means certain and 1/2 means even chance.
- Relative frequencyAn estimate of probability from an experiment: the number of times something happened divided by the total number of trials.
- Mutually exclusive eventsEvents that cannot happen at the same time. For these, you add their probabilities, and the probabilities of all outcomes add to 1.
- Independent eventsEvents where one result has no effect on the other. To find the chance of both happening, multiply their probabilities.
- Tree diagramsA branching picture showing all possible outcomes of events in order. Probabilities go on the branches and you multiply along them.
- AveragesSingle numbers that sum up a set of data. Mean is total divided by count, median is the middle value, mode is the most common, and range is the biggest minus the smallest.
- Mean from a frequency tableWhen data is in a table, multiply each value by its frequency, add these up, then divide by the total frequency.
- Scatter graphs and correlationA scatter graph plots pairs of data as points. Correlation describes the pattern: positive (both rise), negative (one rises, one falls) or none.