Four ways to describe data
When we collect numbers, four useful values help us describe them: the mode, the median, the mean and the range. The first three tell us about a typical or middle value, while the range tells us how spread out the numbers are.
Key idea
- Mode = the value that appears most often.
- Median = the middle value when the numbers are put in order.
- Mean = add all the numbers, then divide by how many there are.
- Range = largest value − smallest value.
Working them out
Worked example
Marks: 3, 5, 5, 7, 10.
Mode = 5 (it appears twice).
Median = 5 (the middle number).
Mean = (3 + 5 + 5 + 7 + 10) ÷ 5 = 30 ÷ 5 = 6.
Range = 10 − 3 = 7.
Remember
- Always put numbers in order before finding the median.
- For an even count, the median is the mean of the two middle numbers.
- The mean can be a value that is not in the list.