Question

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EXERCISE 12(A)
1. In each of the following, check whether or not the given ratios form a proportion :
(i) 8: 16 and 12:15
(ii) 16 : 28 and 24 : 42 (iii) 12 : 3 and 8 = 2
15
(iv) 25 : 40 and 20 : 32
10
7
(v)
and
(vi) and 14: 16
18 12
8
2. Find the value of x in each of the following proportions :
(1) X: 4 = 6:8
(ii) 14 : x = 7:9
(iii) 4:6 = x: 18
(iv) 8:10 = X: 25
(v) 5:15 = 4: x
(vi) 16 : 24 = 6 : X
3.
Find the value of x so that the given four numbers are in proportion :
(i) X, 6, 10 and 15
(ii) X, 4, 15 and 30
(iii) 2, X, 10 and 25
(iv) 4, X, 6 and 18
(v) 9, 12, x and 8
(vi) 4, 10, 36 and x.
4. The first, second and the fourth terms of a proportion are 6, 18 and 75, respectively. Find
its third term.
5. Find the second term of the proportion whose first, third and fourth terms are 9, 8 and 24,
respectively.
6. Find the fourth term of the proportion whose first, second and third terms are 18, 27 and
32 respectively.
7. The ratio of the length and the width of a school ground is 5 : 2. Find the length, if the
width is 40 metres.
8. The ratio of the sale of eggs on a Sunday and that of the whole week at a grocery shop
was 2: 9. If the total value of the sale of eggs in the same week was 360, find the value
of the sale of eggs that Sunday.
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(Ans.
Ans.)
ively.
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Proportion (Including Word Problems)​

Answer 1

Answer:

(i) 8 : 16 and 12 : 15

Since 8 : 16 = 8/16 = 1/2

and 12 :  15= 12/15 = 4/5

∴ Ratio 8 : 16 ≠ ratio 12 : 15, they are not in a proportion.

(ii) 16 : 28 and 24 : 42

Since 16 : 28 = 16/28 = 4/7

and 24 : 42 = 24/42 = 4/7

∴ Ratio 16 : 28 and 24 : 42 are equal, so they form a proportion.

(iii) 12 ÷ 3 and 8 ÷ 2

Since 12/3 = 4 and 8/2 = 4

∴ Ratio 12 ÷ 3 and 8 ÷ 2 are equal, so they

form a proportion.

(iv) 25 : 40 and 20 : 32

Since 25 : 40 = 25/40 = 5/8

and 20 : 32 = 20/32 = 5/8

∴ Ratio 25 : 20 and 20 : 32 are equal, so

they form a proportion.

(v) 15/18 and 10/12

Since 15/18 = 5/6 and 10/12 = 5/6

∴ Ratio 15/18 and 10/12 are equal, so they form a proportion.

(vi) 7/8 and 14 : 16

Since 7/8 = 7/8 and 14 : 16 = 14/16 = 7/8

∴ Ratio 7/8 and 14 : 16 are equal, so they form a proportion.

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