This is a basic question from ML aggarwal book of class 10th, chapter 7, ratio and proportion., ICSE board
In this question we have been given three numbers, and we have to find the fourth proportional to them.
Ques2, exercise 7.2
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This is a basic question from ML aggarwal book of class 10th, chapter 7, ratio and proportion., ICSE board
In this question we have been given three numbers, and we have to find the fourth proportional to them.
Ques2, exercise 7.2
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Solution:
(i) 3, 12, 15
Consider x as the fourth proportional to 3, 12 and 15
3: 12 :: 15: x
We can write it as
3 × x = 12 × 15
So we get
x = (12 × 15)/ 3
x = 60
(ii) 1/3, 1/4, 1/5
Consider x as the fourth proportional to 1/3, 1/4 and 1/5
1/3: 1/4:: 1/5: x
We can write it as
1/3 × x = 1/4 × 1/5
So we get
x = 1/4 × 1/5 × 3/1
x = 3/20
(iii) 1.5, 2.5, 4.5
Consider x as the fourth proportional to 1,5, 2.5 and 4.5
1.5: 2.5 :: 4.5: x
We can write it as
1.5 × x = 2.5 × 4.5
So we get
x = (2.5 × 4.5)/ 1.5
x = 7.5
(iv) 9.6 kg, 7.2 kg, 28.8 kg
Consider x as the fourth proportional to 9.6, 7.2 and 28.8
9.6: 7.2 :: 28.8: x
We can write it as
9.6 × x = 7.2 × 28.8
So we get
x = (7.2 × 28.8)/ 9.6
x = 21.6