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150 multiple-choice questions and 162 flashcards, organised into 7 chapters, written to the Common Core HS Statistics and Probability standards / typical HS Statistics course blueprint. Every question carries a full rationale.
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Common Core HS Statistics and Probability standards / typical HS Statistics course (non-AP) — covers: descriptive statistics (mean, median, mode, range, standard deviation), data visualization, probability (basic rules, conditional, independence), distributions (binomial, normal), sampling, sampling distributions, confidence intervals, hypothesis testing, regression introduction. MCQs reference public Common Core standards.
CoStudy's HS Statistics bank holds 312 items organised into 7 chapters that follow the published blueprint. Every multiple-choice question carries a written rationale explaining why the correct answer is correct and why each distractor is tempting but wrong.
Each chapter follows a domain of the published exam outline. Practise one on its own:
A sample of 12 multiple-choice questions from the bank, with the full rationale shown.
What is the MEAN of 4, 6, 8, 10, 12?
Answer: C — 8 (sum 40, count 5; mean = 40/5 = 8)
Mean: arithmetic average = sum/count = 40/5 = 8. Measure of central tendency. Sensitive to outliers. Use median for skewed data.
What is the RANGE of 4, 8, 10, 15, 20?
Answer: B — 16 (max - min = 20 - 4)
Range = max - min. 20 - 4 = 16. Simplest measure of spread. Limited because uses only two extreme values. IQR (Q3-Q1) more robust.
The mode of the data set {2, 3, 4, 4, 5, 6, 4, 7} is:
Answer: D — 4
D) 4 appears three times — more than any other value. A/B/C) Each appears only once.
If X ~ N(50, 10), P(X > 60) using standardization:
Answer: D — P(Z > 1) ≈ 0.16
D) z = (60−50)/10 = 1. A/B/C) Each is incorrect.
Larger sample size affects CI:
Answer: B — Makes it narrower (more precise) — because SE decreases
B) Standard. A/C/D) Each is incorrect.
For the dataset {3, 7, 8, 12, 20}, which value is closest to the standard deviation (using the population formula)?
Answer: C — 5.8
C) Mean = 10. Deviations: -7, -3, -2, 2, 10 → squares 49, 9, 4, 4, 100 = 166. Variance = 166/5 = 33.2; SD = √33.2 ≈ 5.76. A/B) Underestimates ignoring the extreme value. D) Confuses range or sum of |deviations|.
p-value interpretation:
Answer: A — Probability of observing data this extreme if null is true
A) Standard. B is misinterpretation. C/D) Each is incorrect.
A binomial random variable X has n = 20 and p = 0.3. What is the expected value E(X) and variance Var(X)?
Answer: C — E = 6, Var = 4.2
C) Binomial: E(X) = np = 20(0.3) = 6; Var(X) = np(1−p) = 20(0.3)(0.7) = 4.2. A) Set variance equal to mean — that is Poisson. B) Mis-applied the mean formula. D) Random arithmetic.
ANOVA (Analysis of Variance) tests:
Answer: B — Differences in means across three or more groups simultaneously — F-test compares between-group variance to within-group variance
B) Standard. A/C/D) Each is incorrect.
A regression line has slope b = 2.5 and intercept a = 4. Predict ŷ when x = 8:
Answer: D — 24
D) ŷ = a + bx = 4 + 2.5(8) = 4 + 20 = 24. A) Forgot the slope contribution. B) Forgot the intercept. C) Used 2.5(7.4) error.
A histogram is best for displaying:
Answer: B — Frequency of continuous numerical data
B) Histograms group continuous data into intervals (bins) and show frequency. A) Bar charts handle categorical data. C) Line plots are better for trends over time. D) Scatter plots show bivariate relationships.
Polls and margin of error:
Answer: B — Margin of error typically ~95% confidence interval around point estimate; depends on sample size (larger n → smaller margin); a poll with 50% support ± 3% margin means true value likely 47-53%; doesn't account for non-sampling bias
B) Standard. A/C/D) Each is incorrect.
6 sample cards from the 162 in the bank.
Choose 3 of 7: ?
7C3 = 35.
Always check?
Sample size, methodology, source bias, confounders, statistical vs practical significance.
Bayes' theorem?
P(A|B) = P(B|A) · P(A) / P(B). Updates probability of A given new evidence B.
Independent events?
P(A and B) = P(A) · P(B). One doesn't affect the other (e.g., coin flips).
Placebo?
Inert treatment. Subjects can show effects from belief alone.
Correlation coefficient r?
Measures linear association. -1 to 1. 0 = no linear relationship. Sign = direction, magnitude = strength.
These samples are a small slice. The full bank runs flashcards, multiple choice and timed mock exams with per-chapter progress tracking, on the web and in the iOS app.
The HS Statistics bank holds 312 items: 150 multiple-choice questions, 162 flashcards. 18 of them are on this page to read free, with no signup.
Yes. Every multiple-choice item carries a written rationale that states the controlling principle behind the correct answer and then addresses each wrong option in turn — why it tempts and precisely where it fails. Knowing why the plausible answer was wrong is worth more than knowing which letter was right.
It is organised into 7 chapters that follow the published exam blueprint: Describing Data with Numbers and Graphs; Designing Studies: Sampling and Experimental Design; Probability: Rules, Conditional, Independence; Probability Distributions: Binomial and Normal; Sampling Distributions and Inference for Means and Proportions; Inference for Categorical Data: Chi-Square; Linear Regression and Correlation. The number of questions in each chapter is proportional to that domain's published weight, so working through the bank exposes you to roughly the mix the real exam uses.
Common Core HS Statistics and Probability standards / typical HS Statistics course (non-AP) — covers: descriptive statistics (mean, median, mode, range, standard deviation), data visualization, probability (basic rules, conditional, independence), distributions (binomial, normal), sampling, sampling distributions, confidence intervals, hypothesis testing, regression introduction. MCQs reference public Common Core standards.
The samples on this page are free to read in full, rationales included, with no account. The complete 312-item bank, the timed mock exams and per-chapter progress tracking are part of CoStudy on the web and in the iOS app.
Last reviewed 2026-08-22. Banks are written against the certifying body's published exam outline and re-checked when that outline changes — exams get renumbered, retired and reweighted, and a bank written to a superseded outline teaches the wrong proportions. Figures that are re-indexed annually are deliberately not asserted as rules; the questions test the governing principle instead.