year 8 maths

590 Chapter 9 Data collection, representation and analysis
5 A group of teenagers were weighed and their weights recorded, to the nearest kilogram. The results
are as follows.
56 64 72 81 84 51 69 69 63 57 59 68 72 73 72 80 78 61 61 70
57 53 54 65 61 80 73 52 64 66 66 56 50 64 60 51 59 69 70 85
a Find the highest and lowest weights.
b Create a grouped frequency distribution table using the groups 50–54, 55–59, 60–64 etc.
c Find:
i the range
ii the modal class
d Why is this sample not representative of the whole human population?
6 a Consider the data 5, 1, 7, 9, 1, 6, 4, 10, 12, 14, 6, 3 . Find:
i the mean
ii the median
iii the lower quartile
iv the upper quartile
v the interquartile range (IQR)
b Repeat for the data 6, 2, 8, 10, 2, 7, 5, 11, 13, 15, 7, 4 . What do you notice?
7 In an attempt to find the average number of hours of homework that a Year 8 student completes,
Samantha asks 10 of her friends in Year 8 how much homework they do.
a Explain two ways in which Samantha’s sampling is inadequate to get the population average.
b If Samantha wished to convey to her parents that she did more than the average, how could she
choose 10 people to bias the results in this way?
8 A Year 7 group was asked how many hours
of television they watch in a week. The
results are given in the table.
a How many students participated in the
survey?
b What is the total number of hours of
television watched?
c Find the mean number of hours of television
watched.
d Show this information in a column graph.
9 The number of students in the library is recorded hourly, as
displayed in the graph.
a How many students entered the library when it first opened?
b How many students were in the library at 8 hours after
opening?
c If the library opens at 9 a.m., at what time are there the
most number of students in the library?
d How many students were in the library at 4 p.m.?
TV watched (hours) No. of students
8 5
9 8
10 14
11 8
12 5
Number of students
14
12
10
8
6
4
2
0
0 1 2 3 4 5 6 7 8
Time (hours)
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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