Page 19 - SM inner class 7.cdr

7 2 10 2
Ex am ple 11. Mul ti ply , and . So lu tion : (i) of 15
11 10 11 5
´
So lu tion : The pro ceed is as : 2 ´ 15 = ( 2 15) = 30 = 6
Divide; multiplication of numerators by 5 5 5
multiplication of denominators and we get; (ii) 1 of 12
(7 ´ ´10 ) 4 17
2
=
(11 ´10 ´11 ) 1 ´ 12
4 17
Solve the brackets and we get;
(1 ´12 )
140 =
= (4 ´17 )
1210
12
Divide both numerator and denominator by 10 =
to convert fraction into lowest term and we get; 68
14 = 3 (On simplifying)
= 17
121
7
Operating ‘‘Of ’’ (iii) of ` 72
8
“Of ” works like multiplication
7
For ex am ple : Kavita has 9 tof fees . She gives 8 ´ 72
1
of these tof fees to her sis ter . How many (7 ´72 )
3 rd =
8
tof fees re main with her?
504
First, divide these toffees into three equal =
groups, we can see that each group has 3 8
toffees. = ` 63
1 1 2 1 2
So ´ 9 = 3 toffees Ex am ple 13. Sim plify 3 ´ 5 - 4 ´ 2 .
3 rd 7 3 5 3
1 2 1 2
Which can be written as So lu tion : 3 ´ 5 - 4 ´ 2
1 7 3 5 3
´ 9 = 3 22 17 21 8 374 56
3 = ´ - ´ = -
7 3 5 3 21 5
So, 9 - 3 = 6 toffees remain with Kavita.
-
1870 1176 694 64
Ex am ple 12. Eval u ate : = = 6
105 105 105
2 1 12 7
(i) of 15 (ii) of (iii) of ` 72
5 4 17 8

E xercise 2.2

1. Solve the fol low ing :
2 3 1
(a) 4 ´ (b) 4 ´ (c) 7 ´
7 5 3
2. Eval u ate :
8 7 5 7 1 7 11 5
(a) ´ (b) ´ (c) ´ (d) ´
9 13 9 8 6 16 12 6
5 7 5 5 2 6 5 4
(e) ´ = (f) ´ (g) ´ (h) ´
6 11 12 12 7 7 11 9

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Mathematics In Focus - 7