Question

The third proportional to $8,and12$ is

• A. $8$
• B. $12$
• C. $18$
• D. $24$

Answer 1

The correct option is C

$18$

Let the third proportional be $x$, Then-

so the proportion be, $8:12::12:x$

Now, if $a:b::c:d$be in proportion then

$a\times d=b\times c$ --------------------------------$eq\left(1\right)$

so, now in $8:12::12:x$

$a=8,b=12,c=12,d=x$

So, by $eq\left(1\right)$ we have,

$$\begin{gathered} \Rightarrow 8\times x=12\times 12 \\ \Rightarrow 8x=144 \\ \Rightarrow x=\frac{144}{8} \\ \Rightarrow x=18 \end{gathered}$$

Hence, the third proportion be $18$

Therefore OPTION (iii) is correct