Considering the margin of error, it is found that the 95% confidence interval for the percentage of adults who say vaccines should be required is (64.9%, 71.1%).
It is given by the sample statistic plus/minus the margin of error.
In this problem, 68% of adults say such vaccines should be required, with a margin of error of 3.1%, hence:
68% - 3.1% = 64.9%.
68% + 3.1% = 71.1%.
The 95% confidence interval for the percentage of adults who say vaccines should be required is (64.9%, 71.1%).
More can be learned about confidence intervals at https://brainly.com/question/25890103