year 8 maths

618
11 a 18 minutes b $0.75 c 45 kg
d 62.5 mL e 5.6 days f 3.3 km
12 a 5 1 L
3
b 2000 marbles
c $8
d 45 donuts
13 540
14 Murray, Maeheala, Francesca, Wasim
15 61 1 9 %, 61.1. %
16 68.75%
17 22
18 $24, $24, They are the same. 40
100
multiplication is commutative.
19 B
20 D
21 a 240 cm 2
b 5 cm
c 15 cm by 25 cm
d 375 cm 2
e 135 cm 2
f 56.25%
g 56.25% increase in area
60
× 60 = × 40 as
100
h Multiply the percentage increase in each dimension.
1.25 × 1.25 = 1.5625 = 56.25% increase
i i 21% ii 44% iii 7 % iv 125%
9
j 41.42% increase (√2)
Exercise 4H
1 a $12 b $33.99 c $14.50 d $225
2 a $12 b $108
3 shop A: $270, shop B: $280
4 a $40 b $36 c $40.50 d $15
5 a $440 b $276 c $64 d $41 160
e $5400 f $96.96 g $13.50 h $50.40
6 a $480 b $127.50 c $39 d $104
e $15.40 f $630
7 a $12 b $24 c $37.50 d $63.75
e $97.50 f $4.95
8 a $396 b $11 041.50
c $837 d $746 750
9 shop C: $80, shop D: $75
10 premier rug: $250, luxury rug: $375
11 cash $44.90: credit card: $44.91
12 $265.60
13 $84
14 40%
15 Eastern Bikers, $2320
16 a i $85 ii $630 iii $275 iv $350
b $106.50
c Sam: $720, Jack: $680, Justin: $700
d Sold: $3200, Wage: $960
Exercise 4I
1 a $5 b $16 c $25 d $70
e $1.50 f $8.80 g $0.50 h $0.25
2 a $10, $110 b $5, $55 c $15, $165
d $0.50, $5.50 e $0.10, $1.10 f $12, $132
3 a $68 b $400 c $55
d $2.80 e $35.70 f 57c
4 a $770 b $3300 c $495
d $37.40 e $62 370 f $5.39
5 $80
6 A
7 a $200 b $60 c $8000
d $110 e $100 f $0.90
8 a $320 b $968 c $460
9
10
d $47.50 e $9810 f $5.60
Pre-GST price 10% GST Final cost, including
the 10% GST
$599 $59.90 $658.90
$680 $68 $748
$700 $70 $770
$600 $60 $660
$789 $78.90 $867.90
$892 $89.20 $981.20
$645 $64.50 $709.50
$87.25 $8.73 $95.98
Superbarn Gymea Fruit Market Xmart
a 16.85
b 0.27 kg
c marshmallows –
marked with *
d 1.89 − 0.17
= $1.72
11 a $24 b $240
a $14.99 per kg
b 5th July 2011
c taking the cash
amount to the
nearest 5 cents
d $9.85
e 55 cents
f 5.6% (1 dec. pl.)
c Dividing the post-GST price by 11 gives the GST
included in the price, as 11 × 10% gives 110%.
d As 1.1 × 100 gives 110%, so dividing by 1.1 yields 100%.
12 a $56 b $97 c $789 d $9.87
13 Example, if the price is $100 it goes up to $110, but 10% of
this is not $10, so it does not go back down to $100.
14 As the GST is found on the original 100% value of the
item, 10% of the larger post-GST price will not give the
same amount, as 10% of a larger amount gives a higher
value each time. Remember the post-GST price is 110%.
15 Canada cost ÷ 105 × 100 or cost ÷ 1.05
New Zealand cost ÷ 115 × 100 or cost ÷ 1.15
Singapore cost ÷ 107 × 100 or cost ÷ 1.07
a 8
b $35
c all toys
d $13.55
e 9.09%
(2 dec. pl.)
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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