Statistics · Grades 11 to 12
Centre and spread
Mean, median, mode and range.
The idea
The mean, median and mode describe the centre of a data set. The range describes its spread.
The mean is the sum divided by the count. The median is the middle value after sorting. The range is the largest value minus the smallest.
Worked examples
- How to Find the Mean Find the mean of 4, 9, 7, 8, 12. Three steps, the sum-and-divide method, and the count mistakes to avoid.
- How to Find the Median Find the median of 7, 3, 9, 5, 11. Three steps, the sorting step, and the middle mistakes to avoid.
- How to Find the Range of a Data Set Find the range of 12, 7, 15, 3, 9. Three steps, the largest-minus-smallest rule, and the range mistakes to avoid.
Practice this topic
4 problems with answers.