ACT Math reporting category

ACT Statistics & Probability Practice

Statistics & Probability is the ACT math reporting category about describing data and measuring chance: center and spread, data displays, probability, sampling, and relationships between variables. According to ACT, it makes up 12–15% of scored math questions, under Preparing for Higher Math.

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12–15% of scored Math questions3 original questionsInstant answer checks

At a glance

Statistics & Probability on the ACT: the key numbers

Section and category facts from ACT.org, checked October 9, 2026. Time per question is ACT's section time divided by its question count.
Section	ACT Math: 45 questions in 50 minutes
Scored questions	41 scored, 4 field test
Reporting category	Statistics & Probability (part of Preparing for Higher Math)
Share of scored questions	12–15%, according to ACT
Average time per question	About 67 seconds
Counts toward the Composite	Yes
Practice on this page	3 original questions: Easy, Medium, Hard

What this tests

What does ACT Statistics & Probability test?

Center and spread. Find and compare the mean, median, mode, and range, and decide how an outlier or a new data value changes them.
Data displays. Read tables, frequency tables, bar graphs, histograms, and scatterplots accurately.
Probability of events. Find probabilities of single events, complements, and combined events, including situations described with "and" or "or. "
Two-way tables. Use row and column totals to find probabilities when the question limits the group, such as only the 11th graders.
Sampling and relationships. Judge whether a sample represents a population, and describe associations and trends in paired data.

Practice questions

Practice ACT Statistics & Probability questions

Pick an answer to check it. Each question has one correct choice.

Question 1 of 3Easy

A bag contains 5 red, 7 blue, and 8 green marbles. One marble is chosen at random. What is the probability that the marble is not blue?

Show answer and explanation

Correct answerD. $\frac{13}{20}$

How to solve it

Total marbles: $5 + 7 + 8 = 20$ .
Marbles that are not blue: $5 + 8 = 13$ .
Probability: $\frac{13}{20}$ . The complement gives the same result: $1 - \frac{7}{20} = \frac{13}{20}$ .

Why the other choices miss

\frac{7}{20}

is the probability that the marble is blue, the opposite event.

\frac{2}{5}

counts only the green marbles,

\frac{8}{20}

\frac{7}{13}

compares blue marbles with marbles that are not blue, which is a ratio, not a probability out of all 20.

Question 2 of 3Medium

Books read over the summer by 10 students
Books read	Number of students
2	4
3	3
4	1
6	1
10	1

The table shows how many books each of 10 students read over the summer. What is the median number of books read?

Show answer and explanation

Correct answerA. $3$

How to solve it

List the values in order using the counts: 2, 2, 2, 2, 3, 3, 3, 4, 6, 10.
With 10 values, the median is the average of the 5th and 6th values.
Both of those values are 3, so the median is $3$ .

Why the other choices miss

3.7

is the mean,

37 \div 10

, not the median.

4

is the value in the middle row of the table, which ignores how many students are in each row.

6

averages the smallest and largest values, 2 and 10.

Question 3 of 3Hard

Survey of 200 students by grade and whether they play an instrument
Grade	Plays an instrument	Does not play an instrument
10th	30	50
11th	30	90

The table shows the results of a survey of 200 students. One 11th grader from the survey is chosen at random. What is the probability that this student plays an instrument?

Show answer and explanation

Correct answerB. $\frac{1}{4}$

How to solve it

The question limits the group to 11th graders, so find their total: $30 + 90 = 120$ .
Of those 120 students, 30 play an instrument.
Probability: $\frac{30}{120} = \frac{1}{4}$ .

Why the other choices miss

\frac{3}{20}

divides 30 by all 200 students instead of the 120 eleventh graders.

\frac{3}{10}

is the share of all students who play,

\frac{60}{200}

, which ignores grade.

\frac{1}{2}

reverses the condition: it is the share of instrument players who are in 11th grade,

\frac{30}{60}

Avoid these traps

What mistakes do students make on Statistics & Probability?

Ignoring the frequency column

Students find the median of the values listed in a table without counting how many times each value occurs.

Fix: Expand the table into an ordered list, or keep a running total, before locating the middle value.

Dividing by the wrong total

In conditional probability, students divide by the grand total instead of the total for the group named in the question.

Fix: Circle the group the question chooses from, and use that group's total as the denominator.

Mixing up mean and median

Students compute the mean when the question asks for the median, or assume the two must be equal.

Fix: Reread which measure the question names. In data with a large outlier, expect the mean to move toward it.

Study method

How should you practice ACT Statistics & Probability?

For every probability question, write the denominator in words, such as "all 11th graders," before calculating.
For frequency tables, add a running-total column so you can find the median position quickly.
Estimate first: decide whether a probability should be above or below one half before computing it.
Practice reading tables carefully, including totals you have to compute yourself.
Use Dolphin to practice short mixed sets of statistics and probability questions, then review every table you misread.

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FAQ

Questions about ACT Statistics & Probability

What does Statistics & Probability cover on the ACT?

It covers describing data with center and spread, reading data displays, finding probabilities, sampling, and relationships in data. The questions on this page practice a complement probability, a median from a frequency table, and a conditional probability from a two-way table.

How much of ACT math is Statistics & Probability?

According to ACT, Statistics & Probability makes up 12–15% of scored math questions. ACT groups it under Preparing for Higher Math with Number & Quantity, Algebra, Functions, and Geometry, and that group makes up 80% of scored math questions.

What is the difference between the mean and the median?

The mean is the sum of the values divided by how many values there are. The median is the middle value when the data are in order, or the average of the two middle values when the count is even. An outlier pulls the mean toward it but barely moves the median.

How do I avoid mistakes with two-way tables?

Find the group the question limits you to, such as "an 11th grader chosen at random," and use that row or column total as the denominator. If the table does not show totals, add them yourself before computing.

Should I skip long statistics questions?

Move on for now, but do not leave it blank. ACT does not penalize incorrect answers, so every question should get an answer. If a table question is taking too long, give your best answer, note the question, and return to it if time allows.

Related practice

Sources

Where these facts come from

ACT: Understanding Your ACT Scores: reporting categories, category shares, Composite calculation, and scoring.
ACT: Test Enhancements and Changes: section length, question counts, and optional Science.
ACT: Official test preparation and free practice tests: released ACT questions in the real test format.

ACT facts checked October 9, 2026. Every practice question on this page is original Dolphin practice written to match one ACT reporting category. None is a released ACT item.

ACT® is a trademark registered by ACT, Inc., which is not affiliated with, and does not endorse, Dolphin.

ACT Statistics & Probability Practice

Statistics & Probability on the ACT: the key numbers

What does ACT Statistics & Probability test?

Practice ACT Statistics & Probability questions

How to solve it

How to solve it

How to solve it

What mistakes do students make on Statistics & Probability?

Ignoring the frequency column

Dividing by the wrong total

Mixing up mean and median

How should you practice ACT Statistics & Probability?

Questions about ACT Statistics & Probability

Keep practicing for the ACT

Where these facts come from