AP Statistics Unit 1: Exploring One-Variable Data

Unit 1 covers one-variable data: displays, shape, centre, spread and outliers. At 460 questions it is the largest unit in the AP Statistics bank, and it establishes the vocabulary every later unit depends on.

Practise this unit freeAll Statistics units
460 questions10 CED topics100% with a figure
How this unit behaves

What 460 questions on it look like

This is the largest unit in AP Statistics by practice volume — 460 questions against the subject's other units. Weight your revision accordingly.

It spans 10 CED topics, which is wide enough that "I've studied this unit" is not a meaningful statement. Track your accuracy by topic, not by unit.

100% of the questions come with a figure — a graph, diagram or data display. Reading the figure correctly is most of the work before any content knowledge applies.

Summary Statistics for a Quantitative Variable105
Describing the Distribution of a Quantitative Variable92
Comparing Distributions89
Normal Distributions89
Graphical Representations of Summary Statistics71
The Normal Distribution5
Comparing Distributions of a Quantitative Variable3
Representing a Categorical Variable with Tables2

Questions per CED topic, top 8 of 10.

From the bank

Three real exploring one-variable data questions

Drawn from the practice pool, not from the mock papers.

Graphical Representations of Summary Statistics · Data Analysis · with figure

For farm stand cooperative delta cycle, Q1 for cashless payment use is 10 and Q3 is 17. Which interpretation of the IQR is correct?

  1. AQ3 minus the median, which measures only the upper half of the box instead of the IQR
  2. BThe full range is always 7.
  3. CThe middle 50% of cashless payment use values span 7 units.correct
  4. DExactly 7 shoppers were measured.
  5. EThe mean cashless payment use is 7.
Why C is correct

The IQR is 17 - 10 = 7, describing the spread of the middle 50% of cashless payment use values.

IQR interpretation for farm stand cooperative delta cycle: the important cue is the farm stand cooperative delta cycle setting. Match the method to the way the data are collected or the statistic is computed, then state the conclusion in the language of the stem.

Common mistakes. IQR interpretation for farm stand cooperative delta cycle: Do not treat IQR as a mean or count.

Describing the Distribution of a Quantitative Variable · Using Probability and Simulation · with figure

A statistics class is examining displayed matrix scores. Which panel shows a distribution that is skewed right?

  1. APanel A
  2. BPanel B
  3. CPanel C
  4. DPanel Dcorrect
  5. EPanel E
Why D is correct

Panel D shows a distribution that is skewed right.

This is a strictblind AP Statistics figure item. The stem withholds the data needed to choose an answer, and the answer must be determined from the histogram rendered from render_spec. The matching histogram shape must be identified from the displayed panel. The answer key is recomputed from the structured answer_rule.

Common mistakes. A common error is choosing a familiar-sounding statistics statement without checking the visual evidence in the figure.

Summary Statistics for a Quantitative Variable · Data Analysis · with figure

A graphical output is shown for survey indices. Which panel shows that Group X has the greater range?

  1. APanel A
  2. BPanel B
  3. CPanel C
  4. DPanel D
  5. EPanel Ecorrect
Why E is correct

Panel E shows that Group X has the greater range.

This is a strictblind AP Statistics figure item. The stem withholds the data needed to choose an answer, and the answer must be determined from the dotplot rendered from render_spec. The matching comparison must be identified from the displayed dotplot panel. The answer key is recomputed from the structured answer_rule.

Common mistakes. A common error is choosing a familiar-sounding statistics statement without checking the visual evidence in the figure.

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FAQ

Exploring One-Variable Data questions

When do I use the median instead of the mean?

When the distribution is skewed or has outliers. The median resists them; the mean does not.

How do I describe a distribution?

Shape, centre, spread and unusual features — and always in the context of the variable, not in the abstract.
Last reviewed 2026-08-28. Unit and topic names follow the College Board course framework. Question counts describe the PrepScore practice bank, not the exam.
Topic by topic

Worked questions by topic

4 of this unit’s topics have enough practice questions for a page of their own.

Describing the Distribution of a Quantitative Variable92 questionsSummary Statistics for a Quantitative Variable105 questionsComparing Distributions160 questionsNormal Distributions92 questions
Same course
Unit 2: Exploring Two-Variable Data295 questionsUnit 3: Collecting Data190 questionsUnit 4: Probability, Random Variables, and Probability Distributions100 questionsUnit 5: Sampling Distributions70 questionsUnit 6: Inference for Categorical Data: Proportions107 questionsUnit 7: Inference for Quantitative Data: Means63 questionsUnit 9: Inference for Quantitative Data: Slopes133 questions

Practise exploring one-variable data until the reasoning is automatic.

Real AP questions with a full explanation on every answer, and a mistake bank that only clears when you get it right.

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