# Mean

## Mean – Add up all the numbers and divide by the number of numbers.

**Mean** is the meanest because it takes the **most maths** to figure it out.

This should help you remember that you add up all the numbers and divide by the number of numbers.

**NOTE:**

The mean is the most commonly used mathematical measure of average and is generally what is being referred to when people use the term ‘average’ in everyday language.

**Example 1**

`(840cm)/5=168cm`

The mean height of these five people is 168cm. This is because when you add up all their heights;

150 + 160 + 170 + 180 + 180 = 840cm.

840 divided by the number of people is;

`(840cm)/5=168cm`

## Why is the mean used?

The mean of a set of figures is used because it is a quick method of assessing data. You don’t have to put the data in any order, but you do need to know its limitations.

**Example 2**

A quick way of assessing the data. Take the average using the mean for a large set of figures:

`(10+3+11+7+14+12+15+18 ...\ ...\ .17+15+16)/100` = MEAN

(this is a lot easier than median where you have to put data in order)

**Example 3**

The reason the mean may not be used in some situations is if one or two of the data points vary significantly from the others it can have a more significant effect on the average produced. For example:

The mean salary for these ten staff is £30.7k. However, the data suggests that this mean value might not be the best way to accurately reflect the typical salary, as most workers have salaries in the £12k to £18k range. The mean is being skewed by the two large salaries. Therefore, in this situation, a better measure of central tendency would be the median.