Question

If $9:a::a:16$, then $a$$=$

Answer 1

Two ratios are in proportion then product of their extreme terms is equal to the product of their middle terms.

If $a:b::c:d$

then, $a\times d=b\times c$

Here, $9:a::a:16$

Then, $9\times 16=a\times a$

$\Rightarrow$ $a\times a=9\times 16$

$\Rightarrow$$a^2=144$

$\Rightarrow$$a=\sqrt{144}$

$\Rightarrow$$a=\sqrt{12\times 12}$

$\Rightarrow$$a=12$

Hence, the value of $ais12$