Identifying a median class Revision Card

AI generatedStatisticsKey Stage 3

Identifying a median class.

Put values in order or use cumulative frequencies.
For an odd count, choose the middle observation. For an even count, average the two middle observations.
A median class identifies an interval, not the exact median.

Example 1

Identify the median class.

Given information

Class	Frequency
	3
	5
	7
	2

Add a running total

Class	Frequency	Cumulative frequency
	3	3
	5	8
	7	15
	2	17

Black: given data. Blue: working we add.

Locate the halfway position in the data.

First cumulative total past halfway

The median lies in this class. The table does not give an exact median value.

Median class:

Example 2

Identify the median class.

Given information

Class	Frequency
	4
	5
	8
	2

Add a running total

Class	Frequency	Cumulative frequency
	4	4
	5	9
	8	17
	2	19

Black: given data. Blue: working we add.

Locate the halfway position in the data.

First cumulative total past halfway

The median lies in this class. The table does not give an exact median value.

Median class:

Your turn

Question 1

Identify the median class.

Given information

Class	Frequency
	5
	5
	9
	2

Check answer

Add a running total

Class	Frequency	Cumulative frequency
	5	5
	5	10
	9	19
	2	21

Black: given data. Blue: working we add.

Locate the halfway position in the data.

First cumulative total past halfway

The median lies in this class. The table does not give an exact median value.

Median class:

Question 2

Identify the median class.

Given information

Class	Frequency
	6
	5
	10
	2

Check answer

Add a running total

Class	Frequency	Cumulative frequency
	6	6
	5	11
	10	21
	2	23

Black: given data. Blue: working we add.

Locate the halfway position in the data.

First cumulative total past halfway

The median lies in this class. The table does not give an exact median value.

Median class:

Question 3

Identify the median class.

Given information

Class	Frequency
	7
	5
	7
	2

Check answer

Add a running total

Class	Frequency	Cumulative frequency
	7	7
	5	12
	7	19
	2	21

Black: given data. Blue: working we add.

Locate the halfway position in the data.

First cumulative total past halfway

The median lies in this class. The table does not give an exact median value.

Median class:

Question 4

Identify the median class.

Given information

Class	Frequency
	3
	6
	8
	2

Check answer

Add a running total

Class	Frequency	Cumulative frequency
	3	3
	6	9
	8	17
	2	19

Black: given data. Blue: working we add.

Locate the halfway position in the data.

First cumulative total past halfway

The median lies in this class. The table does not give an exact median value.

Median class:

Question 5

Identify the median class.

Given information

Class	Frequency
	4
	6
	9
	2

Check answer

Add a running total

Class	Frequency	Cumulative frequency
	4	4
	6	10
	9	19
	2	21

Black: given data. Blue: working we add.

Locate the halfway position in the data.

First cumulative total past halfway

The median lies in this class. The table does not give an exact median value.

Median class: