Question

what is the fourth proportion of 2:1 1:5 and 8:4

Answer 1

Step-by-step explanation:

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

ans -6