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AP Statistics 4.3.C Confidence Level, Width & Margin

Practise predicting how confidence level, sample size, and variability change interval width and margin of error for population means.

Syllabus
Effective Fall 2026
Course
AP Statistics

Exam points

  • Hold the sample fixed and recognise that a higher confidence level produces a wider interval.
  • Compare margins of error using sample size and standard deviation, not the sample mean or population size.
  • Use a one-sided p-value to decide which two-sided confidence intervals contain a zero mean difference.

4.3.C—Identify the relationships among sample size, confidence interval width, confidence level, and margin of error… question 1

[Maximum number: 1]

Two meteorologists use the same sample data to calculate the average temperature across the United States. The first meteorologist constructs a 90\% confidence interval, while the second constructs a 95\% confidence interval. Which of the following statements is true?

A

The midpoint of the first meteorologist's interval will be less than the midpoint of the second meteorologist's interval.

B

The midpoint of the first meteorologist's interval will be greater than the midpoint of the second meteorologist's interval.

C

The width of the first meteorologist's interval will be less than the width of the second meteorologist's interval.

D

The width of the first meteorologist's interval will be greater than the width of the second meteorologist's interval.

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