Use the results of Table 4.4 to find the standard deviation of the energy of subsystem A. Note that the total number of microstates accessible to the isolated composite system increases from 12 to 84 when the internal constraint is removed. From the microscopic point of view, it is CHAPTER 4. STATISTICAL MECHANICS 179 EA NA(EA) NB(6 EA) | NANB | PA(EA) 7/84 12/84 15/84 16/84 15/84 12/84 7/84 7 1 6. 2 12 4 3 15 3 4. 16 2 3 15 1 12 1 7 7 Table 4.4: The probability PA(EA) that subsystem A has energy EA given that NA = NB = 2 and Etot = EA + EB = 6.