Averages

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The Mean is a Type of Average

An average is a number that summarises a lot of data. For example, the average national salary is worked out from the salaries of everyone in the country.

The mean is one of several different types of average.

To work out the mean:

Add up all the numbers.

Divide the total by how many numbers there are.

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Example:

The table shows the broadband speeds of a group of residents in a town. What is the mean broadband speed?

First, add up the numbers:

6.7 + 13.6 + 7.9 + 12.2 + 17.1 = 57.5

There are 5 numbers, so divide the total by 5:

57.5 / 5 = 11.5

The mean is 11.5 Mb.

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The Median is Another Type of Average

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

Example:

For the following data, work out the median.

10, 6, 4, 7, 9, 2, 9, 3, 3, 7 and 9.

Firstly, arrange the data in order of size: 2, 3, 3, 4, 6, 7, 7, 9, 9, 9, 10

The median is the middle value, which is 7.

The easiest way to find this is to count in from each end of the arranged data until you have one number left.

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The Mode is Also a Type of Average

The mode is the most common value that appears in a set of data.

Example:

For the following data work out the mode.

10, 6, 4, 7, 9, 2, 9, 3, 3, 7 and 9.

Firstly, arrange the data in order of size: 2, 3, 3, 4, 6, 7, 7, 9, 9, 9, 10

The mode is 9 as it appears more than any other number (three times).