25. Solving a chemistry problem

1. In standard solutions of CdSO4 with different Cd2 activities, the electrode potentials of a cadmium-selective electrode relative to a silver chloride electrode were measured
acd, mol/l 1.0*10-1 1.0*10-2 1.0*10-3 1.0*10-4 1.0*10-5
E, mV -75.0 -100 -122 -146 -170
Based on these data, a calibration graph was constructed in coordinates E - paCd. The test solution of cadmium salt with a volume of 10.00 ml was diluted with water to 50.00 ml in a volumetric flask and the electrode potential of the cadmium selective electrode in the resulting solution was measured - Ex, mV -116
Determine the activity (mol/l) of the test solution of cadmium salt