What is an average?

The average value is a number that is typical for a set of figures. The average is like the middle point of the numbers. Finding the average helps you do calculations and also makes it possible to compare sets of numbers.

For example you might spend between £20 and £100 a week on shopping. Finding the average amount you've spent per week will help you plan your month's spending. The average weekly spend gives you an idea of whether you're spending more or less than you plan to.

There is more than one type of average you can have. The type used most often is the mean value. When people talk about the average of something, like average price, average wage or average height, they are usually talking about the mean value.

The mean value of the weekly spending shown in the graph is £46. Can you see that this is about in the middle of the five different amounts shown? Factsheet 2 explains how to work out mean values. The activity in this module is all about this too.

The mean value can be useful for comparing things. For example you can find the goal average for a football team by finding the mean value of the goals scored per match. When you compare goal averages of two teams you are comparing mean values.

Mean values can be worked out for the weather too. If the mean winter temperature increases every year then you might think that global warming is a serious problem (see the chart below).