In a hypothetical experiment two diffusion weighted signals (within a voxel) S1 = 100, and S2 = 50 were collected using respective b-values of 20 s/mm2 and 1000 s/mm2 respectively. What is the value of diffusion constant D? Group of answer choices 1.02 x 10-3 mm2/s 0.68 x 10-3 mm2/s 0.45 x 10-3 mm2/s 0.71 x 10-3 mm2/s