2.1.1065 Part 1 Section 18.17.7.341, VARPA

a.   The standard does not specify what happens if population size is 0.

Office returns #DIV/0! if population size is 0.

b.   The standard does not specify how function arguments map to formula variables.

Office maps x to a population value, x-bar to AVERAGE(argument-1, argument-2,...,argument-n) and n to population size.