Question

A certain organization wants to know the opinion of the adult residents, 18 years of age or older, of Johnson City about banning smoking in all public restaurants. Specifically, they want to know what proportion of those adults are in favor of banning smoking in all public restaurants. They organize a survey and select a simple random sample of 200 adult residents and ask them "Do you think that smoking should be banned from all public restaurants?" In the sample, 140 people answered "yes." What is the population of interest in this case?

Answer 1

The population of interest is adults, 18 years old of older, who reside in Johnson city.

This population consists in the entirety of the people who fulfill those characteristcs. For example, if 1 million people 18 years of age or older reside in Johnson city, then the population of interest is 1 million people.

The 200 hundred people surveyed is a sample. Statistically, many things about a population can be inferred from a sample thanks to the central limit theorem, which states that if a population has a normal distribution (most populations do), then, its characteristics can be approximately described through sampling a small but representative subset of that population.