A metal surface is illuminated by light of two different wavelengths $\text{248}\text{nm}$ and $\text{310}\text{nm}$. The maximum speeds of the photoelectrons corresponding to these wavelengths are ${\mathrm{u}}_1$ and ${\mathrm{u}}_2$ respectively. If the ratio $\frac{{\mathrm{u}}_1}{{\mathrm{u}}_2}=\frac{2}{1}$ and $\text{hc}\text{=}\text{1240}\text{eVnm}$, the work function of the metal is nearly