Chapter 7: Fractions

(a)

(i) The shaded portion is 1 / 2

(ii) The shaded portion is 2 / 4 = (2 / 2) / (4 / 2) = 1 / 2

(iii) The shaded portion is 3 / 6 = (3 / 3) / (6 / 3) = 1 / 2

(iv) The shaded portion is 4 / 8 = (4 / 4) / (8 / 4) = 1 / 2

Hence, all fractions are equivalent.

(b)

(i) The shaded portion is 4 / 12 = (4 / 4) / (12 / 4) = 1 / 3

(ii)The shaded portion is 3 / 9 = (3 / 3) / (9 / 3) = 1 / 3

(iii) The shaded portion is 2 / 6 = (2 / 2) / (6 / 2) = 1 / 3

(iv) The shaded portion is 1 / 3

(v) The shaded portion is 6 / 15 = (6 / 3) / (15 / 3) = 2 / 5

All the fractions in their simplest form are not equal

Hence, they are not equivalent fractions.

(a) 1 / 2

(b) 4 / 6 = (4 / 2) / (6 / 2)

= 2 / 3

(c) 3 / 9 = (3 / 3) / (9 / 3)

= 1 / 3

(d) 2 / 8 = (2 / 2) / (8 / 2)

= 1 / 4

(e) 3 / 4

(i) 6 / 18 = (6 / 6) / (18 / 6)

= 1 / 3

(ii) 4 / 8 = (4 / 4) / (8 / 4)

= 1 / 2

(iii) 12 / 16 = (12 / 4) / (16 / 4)

= 3 / 4

(iv) 8 / 12 = (8 / 4) / (12 / 4)

= 2 / 3

(v) 4 / 16 = (4 / 4) / (16 / 4)

= 1 / 4

The following are the equivalent fractions

(a) and (ii) = 1 / 2

(b) and (iv) = 2 / 3

(c) and (i) = 1 / 3

(d) and (v) = 1 / 4

(e) and (iii) = 3 / 4

(a) Given

2 / 7 = 8 / ☐

2 × ☐ = 7 × 8

☐ = (7 × 8) / 2

= 28

(b) Given

5 / 8 = 10 / ☐

☐ = (8 × 10) / 5

= 16

(c) Given

3 / 5 = ☐ / 20

☐ = (3 × 20) / 5

= 12

(d) Given

45 / 60 = 15 / ☐

☐ = (15 × 60) / 45

= 20

(e) Given

18 / 24 = ☐ / 4

☐ = (18 × 4) / 24

= 3

(a) We require denominator 20

Let M be the numerator of the fractions

∴ M / 20 = 3 / 5

5 × M = 20 × 3

M = (20 × 3) / 5

= 12

Therefore, the required fraction is 12 / 20

(b) We require numerator 9

Let N be the denominator of the fractions

∴ 9 / N = 3 / 5

3 × N = 9 × 5

N = (9 × 5) / 3

= 15

Therefore, the required fraction is 9 / 15

(c) We require denominator 30

Let D be the numerator of the fraction

∴ D / 30 = 3 / 5

5 × D = 3 × 30

D = (3 × 30) / 5

= 18

Therefore, the required fraction is 18 / 30

(d) We require numerator 27

Let N be the denominator of the fraction

∴ 27 / N = 3 / 5

3 × N = 5 × 27

N = (5 × 27) / 3

= 45

Therefore, the required fraction is 27 / 45

(a) Given numerator = 9

∴ 9 / D = 36 / 48

D × 36 = 9 × 48

D = (9 × 48) / 36

D = 12

Hence, the equivalent fraction is 9 / 12

(b) Given, denominator = 4

∴ N / 4 = 36 / 48

N × 48 = 4 × 36

N = (4 × 36) / 48

= 3

Hence, the equivalent fraction is 3 / 4

(a) Given 5 / 9 and 30 / 54

We have 5× 54 = 270

9 × 30 = 270

5 × 54 = 9 × 30

Hence, 5 / 9 and 30 / 54 are equivalent fractions

(b) Given 3 / 10 and 12 / 50

We have 3 × 50 = 150

10 × 12 = 120

3 × 50 ≠ 10 × 12

Hence, 3 / 10 and 12 / 50 are not equivalent fractions

(c) Given 7 / 13 and 5 / 11

We have 7 × 11 = 77

5 × 13 = 65

7 × 11 ≠ 5 × 13

Hence, 7 / 13 and 5 / 11 are not equivalent fractions

(a) 48 / 60 = (12 × 4) / (12 × 5)

= 4 / 5

(b) 150 / 60 = (30 × 5) / (30 × 2)

= 5 / 2

(c) 84 / 98 = (14 × 6) / (14 × 7)

= 6 / 7

(d) 12 / 52 = (3 × 4) / (13 × 4)

= 3 / 13

(e) 7 / 28 = 7 / (7 × 4)

= 1 / 4

Total number of pencils Ramesh had = 20

Number of pencils used by Ramesh = 10

∴ Fraction = 10 / 20 = 1 / 2

Total number of pencils Sheelu had = 50

Number of pencils used by Sheelu = 25

∴ Fraction = 25 / 50 = 1 / 2

Total number of pencils Jamaal had = 80

Number of pencils used by Jamaal = 40

∴ Fraction = 40 / 80 = 1 / 2

Yes, each has used up an equal fraction of pencils i.e 1 / 2

(i) 250 / 400

= (5 × 50) / (8 × 50)

= 5 / 8

25 / 40 and 30 / 48 are two more fractions

(ii) 180 / 200

= (9 × 20) / (10 × 20)

= 9 / 10

18 / 20 and 27 / 30 are two more fractions

(iii) 660 / 990

= (2 × 330) / (3 × 330)

= 2 / 3

20 / 30 and 200 / 300 are two more fractions

(iv) 180 / 360

= (1 × 180) / (2 × 180)

= 1 / 2

20 / 40 and 30 / 60 are two more fractions

(v) 220 / 550

= (2 × 110) / (5 × 110)

= 2 / 5

20 / 50 and 40 / 100 are two more fractions

∴ The equivalent fractions are

(i) 250 / 100 = (d) 5 / 8

(ii) 180 / 200 = (e) 9 / 10

(iii) 660 / 990 = (a) 2 / 3

(iv) 180 / 360 = (c) 1 / 2

(v) 220 / 550 = (b) 2 / 5