Question

What is the fourth proportional to $0.12,0.21$ and $8$?

• A. $8.9$
• B. $56$
• C. $14$
• D. $17$

Answer 1

The correct option is C $14$

Let the fourth proportional be $x$.

Then, $\frac{0.12}{0.21}=\frac{8}{x}\Rightarrow x=\frac{8\times 0.21}{0.12}$

$\Rightarrow x=\frac{8\times 21}{12}=14$.