Page 71 - Start Up Mathematics_5

7 = 7 × 15 = 105 Remember
12 12 × 15 180 To find the number by which a

11 = 11 × 9 = 99 fraction should be multiplied
20 20 × 9 180 to change into like fraction,

80 < 99 < 105 < 120 < 216 divide the LCM by the
180 180 180 180 180 denominator of that fraction.
6
2
So, 4 < 11 < 7 < < .
9 20 12 3 5
3
,
Example 11: Arrange 2 , 2 7 13 27 and 1 7 in descending order.
,
5 15 15 25 25
Solution: We first convert mixed fractions to improper fractions.
3
2 = (2 × 5) + 3 = 10 + 3 = 13
5 5 5 5

2 7 = (2 × 15) + 7 = 30 + 7 = 37
15 15 15 15

1 7 = (1 × 25) + 7 = 25 + 7 = 32
25 25 25 25
LCM of 5, 15, 25 = 75 5 5 , 15 , 25

13 = 13 × 15 = 195 5 1 , 3 , 5
5 5 × 15 75

37 37 × 5 185 3 1 , 3 , 1
= = 1 , 1 , 1
15 15 × 5 75
13 13 × 5 65
= =
15 15 × 5 75

27 = 27 × 3 = 81
25 25 × 3 75

32 = 32 × 3 = 96
25 25 × 3 75

195 > 185 > 96 > 81 > 65 or 13 > 37 > 32 > 27 > 13
75 75 75 75 75 5 15 25 25 15

3
So, 2 > 2 7 > 1 7 > 27 > 13 .
5 15 25 25 15

EXERCISE 4.2

1. Arrange the following like fractions in ascending order.

,
,
,
,
,
(a) 15 , 7 , 24 32 21 16 (b) 24 51 48 19 37 , 8
,
,
38 38 38 38 38 38 53 53 53 53 53 53
,
,
(c) 92 , 108 , 67 , 29 , 111 , 46 (d) 15 72 43 38 56
,
,
115 115 115 115 115 115 94 94 94 94 94
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