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The three averages — mean, median and mode — along with the ability to calculate them from frequency tables and grouped frequency tables, are among the most commonly tested statistics topics on all three Edexcel papers.
| Term | Definition |
|---|---|
| Mean | Sum of all values ÷ number of values |
| Median | The middle value when data is arranged in order |
| Mode | The most frequently occurring value |
| Modal class | The class interval with the highest frequency (grouped data) |
| Frequency | How many times a value or class occurs |
| Estimated mean | Mean calculated from grouped data using midpoints (an estimate because we don't know exact values) |
Data set: 3, 5, 7, 7, 8, 10, 12
Mean = (3 + 5 + 7 + 7 + 8 + 10 + 12) ÷ 7 = 52 ÷ 7 = 7.43 (2 d.p.)
Median: 7 values → median is the (7 + 1) ÷ 2 = 4th value = 7
Mode = 7 (appears twice; all others appear once)
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