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AP Statistics 3.4.A Interpreting Proportion Intervals

Practise interpreting confidence intervals for population proportions, explaining confidence through repeated sampling, and using estimates with margins of error.

Syllabus
Effective Fall 2026
Course
AP Statistics

Exam points

  • Interpret an interval as a plausible range for the population proportion, not the sample proportion.
  • Explain confidence level through repeated sampling and the long-run capture rate of intervals.
  • Use estimate plus or minus margin of error to identify the interval in context.

3.4.A—Interpret a confidence interval in context for a population proportion question 1

[Maximum number: 1]

In a random sample of 500 American adults, 210 expressed the belief that journalists have "low" ethical standards. A 95\% confidence interval for the proportion of all American adults who believe that journalists have "low" ethical standards is given by (0.3767, 0.4633). Which of the following is a correct interpretation of the confidence level of 95\%?

A

There is a 0.95 probability that the true proportion of all American adults who believe that journalists have "low" ethical standards is between 0.3767 and 0.4633.

B

We are 95\% confident that the true proportion of all American adults who believe that journalists have "low" ethical standards is between 0.3767 and 0.4633 .

C

If the proportion of American adults who believe that journalists have "low" ethical standards is calculated for repeated random samples of 500 adults, 95\% of these sample proportions will fall between 0.3767 and 0.4633 .

D

If a confidence interval for the proportion of American adults who believe that journalists have "low" ethical standards is calculated for repeated random samples of 500 American adults, approximately 95\% of these intervals will contain the true population proportion.

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