\[\sqrt{\frac{1}{16}x^{6}y^{4}} = \frac{1}{4}x^{3}y^{2};\]
\[x = 2;\ \ y = 5:\]
\[\frac{1}{4} \cdot 2^{3} \cdot 5^{2} = \frac{1}{4} \cdot 8 \cdot 25 =\]
\[= 2 \cdot 25 = 50.\]