image 23.11 Legalizing marijuana. An October 2015 Gallup Poll found that 58% of the American adults surveyed support the legalization of marijuana in the United States. The poll had a margin of sampling error of ±4 percentage points at 95% confidence.

  1. (a) Why do the results of this survey suggest that a majority of American adults support the legalization of marijuana in the United States?

  2. (b) The survey was based on 1015 American adults. If we wanted the margin of sampling error to be ±2 per-centage points at 95% confidence, how many Americans would need to be surveyed?