19

26

12

30

16

21

12

12

**Averages**

LI: We are learning about different

ways to work out averages

**Mean**

**Why**

**What**

Is an average?

is it useful?

the

is the most commonly used average

Add up all of the answers and divide the result by the number of answers

3

8

10

4

5

6

How many school lunches have you had this term?

3 + 8 + 10 + 4 + 5 + 6 = 36

There are 6 pupils so the mean number of school lunches is

36 ÷ 6 = 6

**Median**

the

is the middle number

Put all of the results in number order and the median is the one which is in the middle.

3

8

10

3

5

How many pencils are in your pencil case?

When the numbers are put in order 5 is in the middle so the median is

**Mode**

the

is the value which occurs most often

Count how many times each answer appears, the most common value is the mode.

5

8

10

4

5

2

How many house points do you have?

The value 5 appears twice all the other values only appear once so the mode is

5

3

4

5

6

8

10

5

If the sample size is an even number then the median is the MEAN of the two middle numbers.

6 + 5 = 11

11 ÷ 2 = 5.5

10

1

10

2

0

3

How many cousins do you have?

The value 10 appears twice all the other values only appear once so the mode is

10

red

What is your favourite colour?

The answer red is the most common answer so the mode is

red

red

pink

blue

red

green

**Range**

the

The difference between the largest

Subtract the smallest value from the largest value to find the range.

3

8

10

4

5

6

How many school lunches have you had this term?

10 - 3 = 7

The difference between the highest and lowest values is 7 so the range is

**7**

and the smallest value

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

------------------------------------------------------------------------

Monday

Tuesday

Thursday

Wednesday

Days

Rainfall in millimetres

Daily rainfall for the week beginning 04/11/13

**Averages**

Add up all of the answers and divide by the number of answers

Put all of the answers in number in order and the median is the one which is in the middle

Count how many times each answer appears, the one that appears the most often is the mode

Subtract the smallest value from the largest value to find the range

Range

Mode

Median

Mean

**Example of bar chart with mean**

**Progressive set of results for**

advanced examples.

advanced examples.

**Lesson plan and resources for teaching about averages**

**Start here**

3

8

10

3

5

Do you think the mode is a good way of finding the average number of cousins for this group?

You can use the mode for results which aren't numbers!

2

1

3

5

0

4

How many cousins do you have?

Everyone has a different answer

so there is no mode