year 8 maths

260 Chapter 4 Fractions, decimals, percentages and financial mathematics
Exercise 4K
UNDERSTANDING AND FLUENCY
1–8 2–4, 5(½), 6–9 4, 5(½), 6, 7(½), 8, 9
1 If 10% of an amount of money is $75 . How much is 1% of that amount?
A $1 B $7.50 C $75 D $750
2 If 10% of an amount of money is $22 . How much is 100% of that amount?
A $100 B $2.20 C $22 D $220
3 Which alternative best describes the unitary method when dealing with percentages?
A Work out the factor required to multiply the given percentage to make 100% .
B Find the value of 1% and then multiply to find the value of percentage required.
C Once you find the full amount, or 100% of the amount, this is known as ‘the unit’.
D Find what percentage equals $1 and then find the given percentage.
Example 32
Example 33
4 If 6% of an amount of money is $30 , how much is the full amount of money?
5 Calculate the full amount of money for each of the following.
a 3% of an amount of money is $27
b 5% of an amount of money is $40
c 12% of an amount of money is $132
d 60% of an amount of money is $300
e 8% of an amount of money is $44
f 6% of an amount of money is $15
6 If 4% of the total bill is $12 , how much is 30% of the bill?
7 Calculate:
a 20% of the bill, if 6% of the total bill is $36
b 80% of the bill, if 15% of the total bill is $45
c 3% of the bill, if 40% of the total bill is $200
d 7% of the bill, if 25% of the total bill is $75
8 What is the total volume if 13% of the volume is 143 litres?
9 What is the total mass if 120% of the mass is 720 kg ?
PROBLEM-SOLVING AND REASONING
10, 11(½), 14 11(½), 12, 14, 15 11(½), 12, 13, 15, 16
Example 34
10 A necklace in a jewellery store has been discounted by 20% . If the sale price is $240 , what was the
original price of the necklace?
11 Find the original price of the following items.
a A pair of jeans discounted by 40% has a sale price of $30 .
b A hockey stick discounted by 30% has a sale price of $105 .
c A second-hand computer discounted by 85% has a sale price of $90 .
d A second-hand textbook discounted by 80% has a sale price of $6 .
e A standard rose bush discounted by 15% has a sale price of $8.50 .
f A motorbike discounted by 25% has a sale price of $1500 .
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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