In what situations is it helpful to use a sample of a population? Mark all that apply.

A sample is useful when studying everyone in a population would be impractical. If the population is very large, surveying every member may take too long or cost too much, so choices A, C, and D are correct. A sample is not especially helpful just because a population is very small, and it cannot fix a mismatch between the population and the survey question.

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