Edexcel Maths Answer Key

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Edexcel IGCSE Maths 1
Answers to activities and exercises

Unit 1
1NUMBER 11 EXERCISE 1
1 6
2 3 1 3

2 7

2 3 3 , 75% 4

11 0.15, 15% 16 3 21
1 4 11 6

12 0.075, 7.5% 17 3 22
2 5 41 7

14 19

EXERCISE 1*
1 6 11 16
2 7 3 8 2 3 3 40

2 7 12

2 3 3 40 4 5

3 8 13

3 18 1 15 4 9

4 9 14

7 11 5 6 3 8

5 10 15

1 2 5 6 7 40

17 680 22 3.1 27 41.86

18 910 23 24 28 49.88

19 0.765 24 18

20 0.095 25 26.25

21 39 26 42.84

EXERCISE 2
1 6 11 16 5 –20 –6 3 2 7 12 17 –8 –3 –6 10 3 8 13 18 13 –10 –2 4 4 –17 9 –12 14 –5 5 13 10 28 15 3

EXERCISE 2*
1 –2 6 10 11 12 16 74 2 6 7 18 12 18 17 144 3 23 8 10 13 36 18 196 4 5 9 12 14 13 5 18 10 2 2 3

15 49

EXERCISE 3
1 1.8 6 12.6 litres 11 15% 2 0.272 km 7 £31.80 12 6% 3 5.52 m 8 £64.80 13 10% 4 1.38 cm 9 £45.50 14 15% 5 0.684 10 £71.20 15 5%

IGCSE Maths Answers – Unit 1
1

1 3 1 8 , 20% 5 7 , 35% 13 20 5 18 2 7

3

4 9

2 3 1 , 0.25 4 3 , 37.5% 8 7 3

1 2 1 10 , 0.125 8 2 15 2 3 18 20 5

5

16 5.94 m 18 $9120

17 Percentage increase in value = 19 688 20

468 7800

100 = 6%

60 80 = 2.70% increase. = 3.95% increase. 80 2000

EXERCISE 3*
1 0.75 6 106.25 11 15% IGCSE Maths Answers – Unit 1 2 21 kg 7 68.005 km 12 $836 3 $171 8 86.1 kg 4 11.7 km 9 $80.04 5 52.5 10 $89.18 4.25 34

13 Profit = 4.25; percentage profit =

100 = 12.5%

14 39% 15 0.0402% 16 33.3% 17 250% 18 11.1%; 12.5% 19 There are 500 million telephones in the world, 60 000 in Ethiopia. Population of Ethiopia is 30 million. 20 1976 1986 1996 Largest tin (p/g) Smallest tin (p/g) 0.0359 0.0493 0.0607 0.1 0.0738 0.16 % increase in cost ’86–’96 21.6 60

% increase in cost ’76–’86 Largest tin Smallest tin 69.1 102.8

Inflation was much higher between 1976 and 1986. If the larger tin were bought in 1976 you would get 37.3% more for your money. In 1986 you would get 64.7% more for your money and in 1996 you would get 117% more.

ACTIVITY 1
Neurons: 1011 Connections: 1015 Connections per second = 1015 ÷ (60 60 24 365 75) half a million

EXERCISE 4
1 6 11 16 21 26 31 36 105 107 103 102 5.68 102 56 000 7 970 000 1.4 102 2 7 12 17 22 27 32 37 105 1013 102 4.56 102 3.84 101 4 090 000 987 600 5 10 3 8 13 18 23 28 33 1010 1011 103 6.78 101 7.0605 102 678 900 1000 4 9 14 19 24 29 34 1010 102 108 1.2345 102 1.23 108 560 10 000 5 10 15 20 25 30 35 103 105 101 6.7 107 4000 65 000 8.4 109

EXERCISE 4*
1 6 11 16 21 25
2

4.5089 104 2 8.705 104 3 2.983 107 4 7.654 107 5 103 6 5 0 21 7 10 8 10 or 1 9 10 10 108 10 12 106 13 6.16 106 14 2.7 108 15 4 10 100 or 1 4 16 42 4 7.083 10 17 9.1125 10 18 2.43 10 19 2.5 10 20 3.46 108 9.653 108 22 4 103 23 1010 24 1000 Saturn 10 cm, Andromeda Galaxy 1 million km, Quasar 1000 million km

EXERCISE 5
1 6 11 16 800 0.56 3.0 9.9 104 2 90 000 7 0.506 12 9.1 3 3740 8 0.105 13 1 105 4 80 300 9 34.78 14 1.1 105 5 0.44 10 0.65 15 1 105

EXERCISE 5*
1 6 11 16 10 2 5000 0.0068 7 0.0495 7.0 12 78.2 9.877 104 3 45.7 8 0.000568 13 1.06 105 4 89 500 5 0.067 9 9.00 10 2.08 14 1.057 105 15 9.88 104

REVISION EXERCISE 6
1 105 6 11
12 25 1 30

2 102 7 0.48 12 10
8

3 4570 8 13
21 8 1 16

4 4.57 9 2.625 14 4.2

103

5 3700 10
1 3

7 9

15 420 20 0.046

16 4 21 9.2

17 14.4 22 5 104

18 0.05 23 2.04
0.6 12

19 0.046 24 45.12 km

25 Profit = $0.60; percentage profit = 26 15%

100 = 5%

REVISION EXERCISE 6*
1
1 4

2

3 7

3

5 12

4 8.1 9 102

103

5 8.10 10 108

103

6 0.0456 7 45 600 8 1012 8 7 12 5.28 10 13 8 102 11 1.586 10 14 To increase 80 by 10% = 88. To decrease 120 by 30% = 84. the first by 4. 15 Profit = 162 000; percentage profit = 162 000 900 000

100 = 18%

16 0.04 13.50 = 0.54; 13.5 – 0.54 = 12.96 17 $42 928.40 18 2 cents loss

1ALGEBRA 11 ACTIVITY 2
3 6, half number added.

INVESTIGATE
Substituting any value of x gives the same values for both expressions because x3 + x2 + x + 1 = (x + 1)(x2 + 1).

IGCSE Maths Answers – Unit 1
3

EXERCISE...
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