Question

What should be added to each of the numbers $13,17$ and $22$ so that the resulting numbers are in continued proportion?

• A. 3
• B. 5
• C. 2
• D. 4

Answer 1

The correct option is A 3

Let the required number to be added is $x$.
$\therefore 13+x,17+x$ and $22+x$ are in continued proportion.
$\Rightarrow \frac{13+x}{17+x}=\frac{17+x}{22+x}$
i.e. $(13+x)(22+x)=(17+x{)}^2$
$\Rightarrow 286+35x+x^2=289+34x+x^2$ i.e. $x=3$
$\therefore$ Required number $=3$.