Faculties'
The plural of faculty is faculties.
The plural possessive form of "experiments" is "experiments'."
The plural is Ph.Ds or PhDs (people) and the plural possessive is PhDs'.(the abbreviation with a period or periods is normally used after a name)
The plural possessive form of "experiments" is "experiments'".
The plural form of the noun Copernicus is Copernicuses.The plural possessive form is Copernicuses'.Example: The Copernicuses' home was in Torun, a city of the Polish kingdom.