1. Starter Use the frequency diagram to find: Mode Median Range
Explain why we can’t find the mean for this data?

2. Frequency Objectives Key Vocabulary
To be able to present continuous data in grouped frequency distributions
To use grouped frequency data and represent it using histograms
Key Vocabulary
Frequency
Histogram
Class Width

3. 7, 8, 7, 6, 7, 5, 7, 6, 7, 6, 8, 6, 7, 7, 6, 6, 7, 5, 6, 8
 5, 5, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8
There are different ways of presenting data to make it easier to understand.
Shoe Size
Frequency 5 2 6 7 8 3

4. For some data it makes sense to use a grouped frequency distribution
140cm, 179cm, 160cm, 151cm, 167cm, 153cm, 142cm, 141cm, 161cm,
157cm, 171cm, 152cm, 162cm, 164cm, 151cm, 166cm, 141cm, 166cm,
153cm, 146cm, 159cm, 159cm, 151cm, 168cm, 157cm, 138cm,
152cm, 149cm, 158cm, 178cm, 167cm, 148cm
For some data it makes sense to use a grouped frequency distribution
Frequency
Height (cm)
130
140
170
150
160
180
Histogram showing frequency of heights in sample 12 10
Height (cm)
Frequency
130- 1
140- 7
150- 12
160- 9
170- 3
180- 8 6 4 2

5. The points are the midpoints of the class intervals
Another way to present frequency data is with a frequency polygon
Frequency polygons showing the frequency of heights for boys and girls in sample
Histogram showing frequency of heights in sample 12 10
We can compare more than one frequency polygon in the same graph 8
Frequency 6
Boys 4 2
Girls
130
140
150
160
170
180
Height (cm)

6. The area is given by the width x height
It is possible to have a histogram with unequal class widths
Height (cm)
Frequency
130- 15
145- 30
155-
160- 40
165-
175-
The frequency is given by the area of the bars.
The area is given by the width x height
Frequency Density 7 6 5 4 3 2 1
130
140
150
160
170
180
190
Height (cm)

7. Frequency Density So that …
The Frequency Density is the frequency ÷ class width
So that …
Class Width x Frequency Density = Frequency
Frequency Density 7 6 5 4 3 2 1
130
140
150
160
170
180
190
Height (cm)

8. For more revision on histograms, refer to www. mymaths. co
For more revision on histograms, refer to and these online lessons ….
 Data  Charts and Graphs  Histograms
 GCSE Stats  Presenting Data  Histograms