In a constant-pressure cake filtration with an incompressible cake layer, volume of the filtrate (V) is measured as a function of time t. The plot of t/V versus V results in a straight line with an intercept of 10⁴ s m^-3. Area of the filter is 0.05 m², viscosity of the filtrate is 10^-3 Pa s. and the overall pressure drop across the filter is 200 kPa. The value of the filter-medium resistance (in m^-1) is