### Averages: Mean, Median and Mode

Averages give us the "common" value in a set of data. There are 3 ways to measure the average:

1. | Mean | ||

is the most commonly used average. It is calculated by adding up the set of values and then dividing that sum, by the number of values used:
| |||

2. | Median | ||

order the set of values by size then work out the middle value | |||

3. | Mode | ||

the value that occurs most often |

- Example 1. Find the mean, median and mode of

15 19 10 17 17 16 18 - Example 2. Find the mean, median and mode of

15 22 21 18 15 4 12 5 23

**Median**

**(a)** order the numbers

10, 15, 16, 17, 17, 18, 19

**(b)** find the median which is the middle number:

10, 15, 16, 17, 17, 18, 19 = 17

**Mode** find the most common value: 17 occurs twice so it is 17

**Median**

**(a)** order the numbers

4, 5, 12, 15, 15, 18, 21, 22, 23

**(b)** find the median which is the middle number:

4, 5, 12, 15, 15, 18, 21, 22, 23 = 15

**Mode** find the most common value: 15 occurs twice so it is 15

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