Question

2. Find the values of x for which the following ratios are in proportion:
(b) x: 48 :: 18:12
(c) 7:21:22:
(a) 3:4:: X: 20​

Answer 1

Answer:

b. 72

c

a 15

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Answer 2

(a) the value of x is 15

(b) the value of x is 72

(c) the value of x is 66

Step-by-step explanation:

(a) 3 : 4 :: x : 20

Since 3, 4, x and 20 are in proportion, then

1st term × 4th term = 2nd term × 3rd term

$\Rightarrow 3\times 20=4\times x$

$\Rightarrow x=\dfrac{3\times 20}{4}$

$\Rightarrow x=15$

∴ the value of x is 15.

(b) x : 48 :: 18 : 12

Since x, 48, 18 and 12 are in proportion, then

1st term × 4th term = 2nd term × 3rd term

$\Rightarrow x\times 12=48\times 18$

$\Rightarrow x=\dfrac{48\times 18}{12}$

$\Rightarrow x=72$

∴ the value of x is 72.

(c) 7 : 21 :: 22 : x

Since 7, 21, 22 and x are in proportion, then

1st term × 4th term = 2nd term × 3rd term

$\Rightarrow 7\times x=21\times 22$

$\Rightarrow x=\dfrac{21\times 22}{7}$

$\Rightarrow x=66$

∴ the value of x is 66.