An average is a single value that represents a set of numbers.

## Mean

To calculate the mean:

- add up all the values
- divide by the number of values.

**Example: Work out the mean of the following numbers 2, 4, 2, 3, 7.**

**The mean: Add them all up and divide by the total number of items. **

- Add them up: 2 + 4 + 2 + 3 + 7 = 18
- Number of items = 5
- Mean = 18/5 = 3.6

## Range

The range of a set of data tells you how widely the numbers are spread.

Range = the biggest value – the smallest value.

**Example: Work out the range of the following numbers 2, 4, 2, 3, 7.**

**Range: largest – smallest ** **7 – 2 = 5 **

## Median

The median of a set of data is the middle value when the data values are placed in order.

To work out the median:

- Put the numbers in ascending (increasing) order.
- Cross out the extremes until you are left with one number.
- If you are left with two numbers, add them up and divide by 2.

**Example: Work out the median of the following numbers 2, 4, 2, 3, 7.**

**Median: Put the numbers in ascending order from smallest to the largest**.

2 2 3 4 7

**Then cross the ends off until you are left with one number. If you are left with two, work out the mean of these two numbers. **

~~2~~ ~~2~~ **3** ~~4~~ ~~7~~

## Mode

The mode of a set of data is the value that occurs most often.

**Example: Work out the mode of the following numbers 2, 4, 2, 3, 7.**

**Mode: Most common number. **

**2, 2, 3, 4, 7 ; 2 is the most common. **