Final answer:
The data set is a population if it includes the number of floors in every home within the town; it is a sample if it includes only a subset of all homes.
Step-by-step explanation:
The data set of the number of floors in each home in a town would be considered a population if it includes the number of floors of every single home within the town. Since a population represents the entire set of subjects or items of interest, in this case, if every home is accounted for, it indeed represents the whole population of floors in the town's homes. On the other hand, if the data set includes only the number of floors in a subset of homes within the town, it would be considered a sample since it does not encompass all homes. However, since most studies aim to work with the entire set of data, unless specified otherwise, we would typically assume that all homes are included and therefore, it represents a population.