Given that 5 = 2.236 and 3 = 1.732, then the value of 1 5 + 3 is = ?

Answer: Option C

$$\begin{array}{rl}& \frac{1}{\sqrt{5}+\sqrt{3}}\times \frac{\sqrt{5}-\sqrt{3}}{\sqrt{5}-\sqrt{3}}\\ & =\frac{\sqrt{5}-\sqrt{3}}{5-3}\\ & =\frac{2.236-1.732}{2}\\ & =\frac{0.504}{2}\\ & =0.252\end{array}$$