Given 5 = 2.2361, 3 = 1.7321 , then 1 5 - 3 is equal to ?

Answer: Option C

$$\begin{array}{rl}& \Rightarrow \frac{1}{\sqrt{5}-\sqrt{3}}\\ & =\frac{1}{\sqrt{5}-\sqrt{3}}\times \frac{\left(\sqrt{5}+\sqrt{3}\right)}{\left(\sqrt{5}+\sqrt{3}\right)}\\ & =\frac{\left(\sqrt{5}+\sqrt{3}\right)}{5-3}\\ & =\frac{\left(2.2361+1.7321\right)}{2}\\ & =\frac{3.9682}{2}\\ & =1.9841\end{array}$$