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The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?

Answer! if you don’t mind, can you explain

Identify all the cases where non-probability sampling is used when attempting to study the characteristics of a large city. studies on every subject in the population divide a population in groups and obtain a sample studies with a limited amount of time demonstrate existing traits in a population studies with the nth person selected