90. Solving a chemistry problem

Calculate the rate constant for the saponification of ethyl acetate with sodium hydroxide at 25°C using the following data:
Time τ from the beginning of the reaction, min 0 10 25 40 55 70
Cell electrical resistance R, Ohm 191 252 315 354 380 402
Initial concentration of ether and alkali: Cef,0=Csh,0=10 mol/m3.
Cell constant b=47.5 m-1. Calculate the rate constant graphically and analytically.