A fully submerged infinite sandy slope has an inclination of $30^\circ{}$ with the horizontal. The saturated unit weight and effective angle of internal friction of sand are $18\:kN/m^3$ and $38^\circ{}$, respectively. The unit weight of water is $10\:kN/m^3$. Assume that the seepage is parallel to the slope. Against shear failure of the slope, the factor of safety (round off to two decimal places) is ______.