year 8 maths

9B
Dot plots and column graphs
531
Example 3
Interpreting a dot plot
Some children were asked the following question in a survey: “How many pets do you have at home?”
The responses are shown in the dot plot below.
Pets at home survey
Number of children
0 1 2 3 4 5 6 7 8
Number of pets
a Use the graph to state how many children have 2 pets.
b How many children participated in the survey?
c What is the range of values?
d What is the median number of pets?
e What is the outlier?
f What is the mode?
SOLUTION
EXPLANATION
a 4 children There are 4 dots in the ‘ 2 pets’ category, so
4 children have 2 pets.
b 22 children The total number of dots is 22 .
c 8 − 0 = 8 Range = highest − lowest
In this case, highest = 8, lowest = 0 .
d 1 pet
As there are 22 children, the median is the
average of the 11 th and 12 th value. In this case,
the 11 th and 12 th values are both 1 .
e the child with 8 pets The main cluster of children has between 0 and
3 pets, but the person with 8 pets is significantly
outside this cluster.
f 1 pet The most common response was 1 .
It has the highest column of dots.
Cambridge Maths NSW
Stage 4 Year 8 Second edition
ISBN 978-1-108-46627-1 © Palmer et al. 2018
Cambridge University Press
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