If the average particle size of the respirable dust sample is 2 m, and if the total weight of the sample is 2 mg, there are 1.8x10 8 particles in the sample and 3860 in a position to diffract assuming true randomness.
(the average particle size of the respirable dust sample; is; 2 m) (the total weight of the sample; is; 2 mg)
the average particle size of the respirable dust sample the total weight of the sample
is is
2 m
2 mg