Explain How does a poll measures public opinion?

An opinion poll, often simply referred to as a poll or a survey, is a human research survey of public opinion from a particular sample. Opinion polls are usually designed to represent the opinions of a population by conducting a series of questions and then extrapolating generalities in ratio or within confidence

Explanation:

The purpose of a poll is to identify how a population feels about an issue or candidate. Many polling companies and news outlets use statisticians and social scientists to design accurate and scientific polls and to reduce errors. A scientific poll will try to create a representative and random sample to ensure the responses are similar to what the actual population of an area believes. Scientific polls also have lower margins of error, which means they better predict what the overall public or population thinks.

Short asnwer:

Opinion polls are usually designed to represent the opinions of a population by asking a series of questions and then extrapolating generalities from responses in ratio or within confidence intervals.

the main reason that the constitution did not proclaim all men to be free and equal is because of the issue of slavery.