Answer:
450,000 registered voters in the district
Step-by-step explanation:
Population of interest is defined as the population that is under study and abouth which information is collected. Population of interest can be people, objects, measurements, and so on.
It is from the population of interest that the researcher draws samples that are studied. Insights from studying the sample will be used to draw conclusions about the population.
In this instance 4,000 voters interviewed is the sample. They were drawn from the population of interest made up of 450,000 registered voters in the district.