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Assuming that A and B mix to form a substitutional solid solution and that all configurations of A and B atoms are equally probable, the number of distinguishable ways of arranging the atoms on the atom sites, if N1=8 and N2=4 is_____ (N1, N2 are the number of atoms in A and B respectively).

Assuming that A and B mix to form a substitutional solid solution and that all configurations of A and B atoms are equally probable, the number of distinguishable ways of arranging the atoms on the atom sites, if N1=8 and N2=4 is_____ (N1, N2 are the number of atoms in A and B respectively). Correct Answer 495

The required equation for the above mentioned problem is (N1+N2)! / ((N1!)*(N2!)). So substituting the value of N1 and N2 we have 12! / (8!*4!) = 495.

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