Range

Range is the difference between the highest and lowest values in a set of data.

Example Find the range of these numbers: 6, 4, 6, 5, 3
Put them in order first as this makes it easier to see the lowest and highest
         3, 4, 5, 6, 6
The lowest number is 3 and the highest is 6.
Find the difference. Subtract 3 from 6
         6 - 3 = 3
The range of this set of data is 3.

Example Compare the range of temperatures for Cardiff and London for a week in July. Temperatures are given in the table in degrees centigrade.

Lets find the range for Cardiff. First put the data into order
      Cardiff: 18, 18, 19, 19, 20, 20, 20
So the lowest temperature for Cardiff was 18° C, the highest was 20° C
The difference between the highest and lowest is
      20 - 18 = 2
So the range of temperature for Cardiff is 2° C.

Now lets do London. First put the data into order.
      London: 19, 20, 20 , 21, 21, 22, 22
The range is the difference between the highest and the lowest. That is
      22 - 19 = 3
So the range for the temperatures in London is 3° C.

We can compare the temperature ranges for London and Cardiff. London has a slightly larger range of 3, compared to a range of 2 in Cardiff. This means that during this week the temperature in London was more variable than in Cardiff.