Question

Find the fourth proportional in $5,\sqrt{75},\sqrt{48}$

• A. $15$
• B. $45$
• C. $12$
• D. $121$

Answer 1

The correct option is C $12$

In $a:b::c:d;d$ is the fourth proportional.
In, $5:\sqrt{75}::\sqrt{48}:d$, product of extremes $=$ product of means
$5\times d=\sqrt{75}\times \sqrt{48}$
$d=\frac{\sqrt{75}\times \sqrt{48}}{5}=\frac{5\sqrt{3}\times 4\sqrt{3}}{5}=4\times 3=12$