How to see it
Four words. Mean: add them up and share equally. Median: put them in order, take the middle. Mode: the most common. Range: biggest take smallest, a measure of spread. Mean shares out, median sits in the middle, mode is the most popular, range is the gap.
A worked example
Order them: 3, 3, 7, 9, 12. The middle is 7. The mode is 3, it appears twice. The range is 12 take 3, 9. The mean is the total, 34, divided by 5, 6.8.
The common mistake: finding the median without ordering
The trap is picking the middle of the list as given, 9. A median needs the numbers in order first.
Try one
The mean of four numbers is 12. Three of them are 8, 11 and 15. What is the fourth?
- A12
- B14
- C48
- D34
Show the answerHide the answer
Right: B, 14
Four numbers with a mean of 12 total 48. The three add to 34, so the fourth is 14.