1

Problem

Find the fourth proportion to 4 , 6 and 8.

2

Step

Let us take the third proportion is

x

3

Step

We can write the above numbers in the proportional form (a: b::c : d)

4:6::8:x

4

Hint

\$a/b::c/d\$

5

Step

Here a = 4 , b = 6 , c = 8 & d = x.

6

Step

Let us find the x value

\$x = (6 × 8) /4\$
x = 12

Choices

7

Choice-A

21 is wrong; it doesn’t follow the proportional relationship between the terms

Wrong 21

8

Choice-B

The proportional relationship between the terms shows that 22 is incorrect

Wrong 22

9

Choice-C

23 is incorrect because it does not match the correct calculation of the fourth proportion

Wrong 23

10

Choice-D

Correct fourth proportion calculation result

Correct 12

11

Answer

Option

D

12

Sumup

Please summarize choices