Range (Cambridge (CIE) IGCSE Maths)
Revision Note
Written by: Mark Curtis
Reviewed by: Dan Finlay
Range
What is the range?
The range is the difference between the highest value and the lowest value
range = highest - lowest
For example, the range of 1, 2, 5, 8 is 8 - 1 = 7
It measures how spread out the data is
Ranges of different data sets can be compared to see which is more spread out
Be careful with negatives
The range of -2, -1, 0, 4 is 4 - (-2) = 6
How do I know when to use the range?
The range is a simple measure of how spread out the data is
The range does not measure an average value
It should not be used if there are any extreme values (outliers)
For example, the range of 1, 2, 5, 80 is 80 - 1 = 79
This is not a good measure of spread
The range is affected by extreme values
Examiner Tips and Tricks
If asked to find the range in an exam, make sure you show your subtraction clearly (don't just write down the answer).
Worked Example
Find the range of the following data.
3.4 | 4.2 | 2.8 | 3.6 | 9.2 | 3.1 | 2.9 | 3.4 | 3.2 |
3.5 | 3.7 | 3.6 | 3.2 | 3.1 | 2.9 | 4.1 | 3.6 | 3.8 |
3.4 | 3.2 | 4.0 | 3.7 | 3.6 | 2.8 | 3.9 | 3.1 | 3.0 |
Range = highest value - lowest value
9.2 - 2.8
The range is 6.4
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