AP Statistics — 20 Essential Multiple-Choice Practice Questions with Explanations
AP Exam Prep · 2025 Edition
AP Statistics Master Practice Exam
20 rigorous multiple-choice questions across all major units — with concept review, examples, and full explanations.
20
Questions
45
Minutes
9
Units
Concept Review
Key Concepts & Formulas
Unit 1 · Exploring One-Variable Data
Describing Distributions
Describe distributions using SOCS: Shape, Outliers, Center, Spread. Recognize symmetric, skewed-left, and skewed-right distributions.
Mean: x̄ = Σxᵢ / n | Median: middle value (sorted) IQR = Q3 − Q1 | Outlier: < Q1−1.5·IQR or > Q3+1.5·IQR
🔑 Tip: In a right-skewed distribution, mean > median. In left-skewed, mean < median. Symmetric: mean ≈ median.
Example
Dataset: 2, 4, 4, 6, 8. Mean = 24/5 = 4.8. Median = 4. IQR = 6−4 = 2. Since mean > median, distribution is slightly right-skewed.
Unit 2 · Exploring Two-Variable Data
Correlation & Least-Squares Regression
The LSRL minimizes the sum of squared residuals. Correlation r measures linear association (−1 ≤ r ≤ 1). r² = coefficient of determination.
ŷ = a + bx | b = r·(sᵧ/sₓ) | a = ȳ − b·x̄ residual = actual y − predicted ŷ
🔑 Tip: r² tells what % of variation in y is explained by x. Outliers and influential points distort regression more than correlation alone.
Example
r = 0.8, so r² = 0.64 → 64% of the variation in y is explained by the linear relationship with x.
Unit 3 · Collecting Data
Sampling & Experimental Design
Random sampling eliminates bias. Experiments require randomization, control, replication, and blinding to establish causation. Observational studies show association only.
🔑 Tip: Mutually exclusive ≠ independent. If A and B are mutually exclusive and both have positive probability, they CANNOT be independent.
Unit 5 · Sampling Distributions
Central Limit Theorem & Sampling Distributions
For large n, the sampling distribution of x̄ is approximately Normal regardless of the population shape (CLT). Standard error measures variability of a statistic.