Question

Fourth proportion :- 2.1 , 1.5 and 8.4 Ans is 10.08 but how ?

Answer 1

Ans is 6, take fourth proportion be X

Answer 2

Hi mahiya

Let me explain you answer

let fourth proportional = x
then


2.1 : 1.5 : 8.4 : x

Now you have two methods to solve this question

1. cross multiply

2.sum of middle = sum of exterm

I solve this question by using cross multiplication method

1. cross multiply

$\frac{2.1}{1.5} = \frac{8.4}{x}$

$2.1x = 8.4 \times 1.5$

$x = \frac{8.4 \times 1.5}{2.1}$

$x = \frac{12.6}{2.1}$


$x = 6$


so, the value of forth proportional is 6



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