Acompany has been rating television programs for more than 60 years. it uses several sampling procedures, but its main one is to track the viewing patterns of 20,000 households. these contain more than 45,000 people and are chosen to form a cross section of the overall population. the households represent various locations, ethnic groups, and income brackets. the data gathered from the sample of 20,000 households are used to draw inferences about the population of all households in the united states. complete parts (a) and (b) below. what strata are used in the sample? choose the correct answer below.