year 8 maths

9F
Frequency histograms and frequency polygons
557
9F Frequency histograms and frequency polygons
Frequency histograms and frequency polygons are graphical representations of a frequency distribution
table so that patterns can be observed more easily.
For example, the data below is represented as a frequency distribution table, a histogram and a frequency
polygon.
As a table
Number
Frequency
0 57
1 29
2 31
3 61
4 26
Frequency
70
60
50
40
30
20
10
0
As a frequency histogram
0 1 2 3
Number
4
Frequency
70
60
50
40
30
20
10
0
As a frequency polygon
0 1 2 3
Number
4
At a glance you can see from the histogram that 0 and 3 are about twice as common as the other values.
This is harder to read straight from the table. Histograms are often used in digital cameras and photo
editing software to show the brightness of a photo.
Let’s start: Test analysis
The results for some end-of-year tests are shown for four different classes, in four different histograms below.
Class 1
Class 2
12
6
10
5
Frequency
8
6
4
2
0
0–9 10–19 20–29 30–39 40–50
Score
Frequency
4
3
2
1
0
0–9 10–19 20–29 30–39 40–50
Score
Cambridge Maths NSW
Stage 4 Year 8 Second edition
ISBN 978-1-108-46627-1 © Palmer et al. 2018
Cambridge University Press
Photocopying is restricted under law and this material must not be transferred to another party.