How it works
This AP Stats Unit 3 practice test has 54 questions of our own on inference for proportions: confidence intervals, significance tests and chi-square tests. It is unofficial and not affiliated with the College Board, which owns AP.
Read the full guide
What Unit 3 covers now
AP Statistics was revised for the 2026-27 school year. The College Board's course description, effective fall 2026 and read October 14, 2026, names Unit 3 Inference for Categorical Data: Proportions and gives it fifteen topics. The bank takes them in order: estimators and sample proportions (4 questions), confidence intervals for one proportion (11), tests for one proportion (11), Type I and Type II errors (7), two proportions (11), and chi-square tests (10). The description weights no topic; the spread is ours.
Where each answer rests
Under every answer is the essential knowledge statement of the description that it rests on. The worked answers were each recomputed from the question's own numbers.
- An interval checks the observed counts of successes and failures. A test checks the counts expected under the null value.
- Never write "accept H0". A large p-value says only that the evidence for the alternative is not convincing.
- Homogeneity compares several samples on one variable. Independence classifies one sample by two variables.
Questions and answers
What is Unit 3 in AP Stats?
Inference for Categorical Data: Proportions. The unit takes about 30 class periods and carries 15 to 25% of the multiple-choice section of the exam.
What should a Unit 3 AP Stats study guide cover?
The sampling distribution of a sample proportion, the one-sample z-interval and z-test, p-values, Type I and Type II errors and power, the two-sample procedures with their combined proportion, and the chi-square tests for homogeneity and independence, each with its three conditions.
Isn't AP Stats Unit 3 Collecting Data?
It was, in the earlier nine-unit course. The course revised for 2026-27 has five units, and sampling methods and experiments moved into Unit 1, Exploring One-Variable Data and Collecting Data.
How many questions are on the AP Stats Unit 3 Progress Check?
About 65 multiple-choice questions and 3 free-response questions, all three on inference, by the course description. Teachers assign it in AP Classroom.
Is this the real AP Stats Unit 3 test?
No. Each of the 54 questions was written for this page from the topics the course description lists. The College Board's questions are in AP Classroom and on its exams, and none is repeated here.