Question

Find the 4th proportional to 9, 17 and 27.
A. 57
B. 48
C. 51
D. 53​

Answer 1

Answer:

51

Step-by-step explanation:

Let x be the required number

Then 9:17=27:x

So 9x=27x17

x=(27x17)/9=51

Answer 2

Answer:

The 4th Proportional number is 51 [Option C]

Step-by-step explanation:

Given :

The numbers in the proportion = 9, 17 and 27

To find :

Their 4th proportional number

Solution :

Consider the 4th proportional number as y

$\longrightarrow$ 9 : 17 : : 27 : y

$\boxed{\sf{Mean \times Mean\:Terms = Extreme \times Extreme \:Terms}}$

• Mean Terms = 17 and 27
• Extreme Terms = 9 and y

➙ 17 × 27 = 9 × y

➙ 459 = 9y

➙ y = 459 ÷ 9

➙ y = 51

4th Proportional number = 51

$\therefore$ The 4th Proportional number is 51 [Option C]