Question

If 9, x, x and 25 are in proportion, find the value of x.

• A. 9
• B. 12
• C. 15
• D. 18

Answer 1

The correct option is C

15

Given: 9, x, x, 25 are in proportion i.e. 9:x :: x:25
$\Rightarrow \frac{9}{x}=\frac{x}{25}$
$\Rightarrow x\times x=9\times 25$
$\Rightarrow x\times x=225$
$\Rightarrow x\times x=15\times 15$
$\Rightarrow x=15$