
Unit 7: Numeracy skills
Averages
There are several ways of expressing an average. The most common way is called a mean . This is one value which is representative of all the numbers in a group. The mean is calculated by adding up all the numbers in a group, then dividing by how many numbers there are.
Example 1 Find the average, or mean, of the following numbers:
2 | + | 6 | + | 4 | + | 8 | + | 5 | + | 5 | = | 3 | 0 | = | 5 |
------------------------------- | ---- | ||||||||||||||
6 | 6 |
Check your answer – in this case, most of the numbers are less than 5 but the very high value of 20 pulls the mean upwards, so the answer is sensible.
Example 3 In a test of numerical ability, students are tested in two groups. Which group has the higher average score?
Group A |
Group B |
---|---|
3 |
7 |
15 |
6 |
8 |
10 |
9 |
11 |
12 |
19 |
13 |
20 |
3 | + | 1 | 5 | + | 8 | + | 9 | + | 1 | 2 | + | 1 | 3 | 7 | + | 6 | + | 1 | 0 | + | 1 | 1 | + | 1 | 9 | + | 20 | |
------------------------------------- | ---------------------------------------- | |||||||||||||||||||||||||||
6 | 6 | |||||||||||||||||||||||||||
= | 6 | 0 | = | 7 | 3 | |||||||||||||||||||||||
---- | ---- | |||||||||||||||||||||||||||
6 | 6 | |||||||||||||||||||||||||||
= | 1 | 0 | = | 1 | 2 | . | 1 | 7 |
Group B has the higher average score
Test yourself with the questions on the next page.
SMILE - Numeracy skills by Tom Frank, Eric Williams and Clare Wright, University of Birmingham Careers Centre adapted by Marion Kelt Glasgow Caledonian University is licensed under a Creative Commons Attribution 3.0 Unported License.