year 8 maths

300 Chapter 5 Ratios and rates
Example 12
Example 13
4 Write each of the following as a simplified rate.
a 12 days in 4 years
b 15 goals in 3 games
c $180 in 6 hours
d $17.50 for 5 kilograms
e $126 000 to purchase 9 acres
f 36000 cans in 8 hours
g 12000 revolutions in 10 minutes
h 80 mm rainfall in 5 days
i 60 minutes to run 15 kilometres
j 15 kilometres run in 60 minutes
5 Find the average rate of change for each situation.
a Relma drove 6000 kilometres in 20 days.
b Fiora saved $420 over three years.
c A cricket team scored 78 runs in 12 overs.
d Saskia grew 120 centimetres in 16 years.
e Russell gained 6 kilograms in 4 years.
f The temperature dropped 5° C in 2 hours.
PROBLEM-SOLVING AND REASONING
6–9, 12 8–10, 12, 13
9–13
6 A dripping tap fills a 9 -litre bucket in 3 hours.
a What is the dripping rate of the tap in litres/hour?
b How long will it take the tap to fill a 21 -litre bucket?
7 Martine grew an average rate of 6 cm /year for the first 18 years of her life.
If Martine was 50 cm long when she was born, how tall was Martine when
she turned 18 ?
8 If 30 salad rolls are bought to feed 20 people at a picnic, and the total cost is
$120 , find the following rates.
a salad rolls/person
b cost/person
c cost/roll
9 The number of hours of sunshine was recorded each day for one week in
April. The results are listed.
Monday 6 hours, Tuesday 8 hours, Wednesday 3 hours, Thursday 5 hours,
Friday 7 hours, Saturday 6 hours, Sunday 7 hours
a Find the average number of hours of sunshine:
i per weekday ii per weekend day
iii per week
iv per day
b Given the rates above, how many hours of sunshine would you expect in April?
10 Harvey finished a 10 kilometre race in 37 minutes and 30 seconds. Jacques finished a 16 kilometre
race in 53 minutes and 20 seconds. Calculate the running rate of each runner. Which runner has a
faster running pace?
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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