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ACT Math

Provider · ACT, Inc. Format · 60 questions · 60 min Chapters · 8 Explorers · 3 interactive
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Test format & strategy

🗻 ACT Math — Official Reporting Categories (60 questions, 60 min)

Reporting Category% of TestKey Topics
Preparing for Higher Mathematics57–60%Broken into 5 sub-areas below
   · Number & Quantity7–10%Integers, ratios, percents, complex numbers, vectors, matrices
   · Algebra12–15%Linear/quadratic equations, systems, inequalities, absolute value
   · Functions12–15%Definition, notation, graphs, transformations, composition, inverse
   · Geometry12–15%Area, volume, angle relationships, trig, coordinate geometry
   · Statistics & Probability8–12%Mean/median/mode, data interpretation, probability, expected value
Integrating Essential Skills40–43%Multi-step problems spanning rates, percentages, proportions, measurement, area/volume

The ACT Math test is 60 multiple-choice questions in 60 minutes — about a minute each — and a calculator is allowed throughout. Questions run roughly easy to hard, drawing on everything from pre-algebra to trigonometry.

What to expect

Five answer choices per question (not four). There is no formula sheet, so the key formulas must be memorized. The content spans number & quantity, algebra, functions, geometry, and statistics & probability.

Questions
60 · multiple choice
Time
60 minutes
Choices
5 per question
Calculator
allowed throughout
▲ Three tactics that score

Don't linger — flag a hard item and move on so easy points aren't lost. Backsolve from the answer choices, and plug in convenient numbers for variables when a question is abstract.

📝 Chapter Quiz
1

Numbers, Percents & Ratios

🗻 Number & Quantity 7–10%  ·  Integers & primes  ·  Fractions, decimals, percents  ·  Ratios & proportions  ·  Real number properties

Pre-algebra fundamentals: fractions and decimals, percentages, ratios and proportions, factors and multiples.

▲ Reference — Proportional reasoning

Percent of a number: \( \tfrac{p}{100}\times N \). A ratio \( a:b \) splits a total into \( a+b \) equal parts. Set up a proportion \( \tfrac{a}{b}=\tfrac{c}{d} \) and cross-multiply.

Percent of
\( \tfrac{p}{100}\times N \)
Percent change
\( \tfrac{\text{new}-\text{old}}{\text{old}} \)
Ratio parts
total \( \div (a+b) \)
Proportion
cross-multiply
Worked example 1.A

What is \( 15\% \) of \( 200 \)? \[ 0.15\times200=30. \]

Worked example 1.B

Split \( 30 \) in the ratio \( 2:3 \). Find the smaller part.

Five parts, each \( 6 \); smaller is 2 parts:

\[ 12. \]

A jacket costs $120 after a 25% discount. What was the original price?
Let original = \(x\). \(0.75x = 120 \Rightarrow x = 160\). Original price: $160.
📝 Chapter Quiz
2

Elementary & Intermediate Algebra

🗻 Algebra 12–15%  ·  Linear equations & inequalities  ·  Systems of equations  ·  Quadratics  ·  Absolute value equations

Linear equations, quadratics, exponents, radicals and absolute value — the algebraic core of the test.

▲ Reference — Algebra essentials

Quadratic formula \( x=\dfrac{-b\pm\sqrt{b^{2}-4ac}}{2a} \); difference of squares \( a^{2}-b^{2}=(a-b)(a+b) \). Exponents: \( a^{m}a^{n}=a^{m+n} \). Absolute value \( |x|=c \) gives \( x=\pm c \).

Quadratic formula
\( \dfrac{-b\pm\sqrt{b^{2}-4ac}}{2a} \)
Difference of squares
\( (a-b)(a+b) \)
Exponents
\( a^{m}a^{n}=a^{m+n} \)
Absolute value
\( x=\pm c \)
Worked example 2.A

Solve \( 3(x-2)=12 \).

\( x-2=4 \):

\[ x=6. \]

Worked example 2.B

Simplify \( \sqrt{50} \). \[ \sqrt{25\cdot 2}=5\sqrt{2}. \]

For what values of \(x\) is \(|2x - 3| < 7\)?
\(-7 < 2x-3 < 7 \Rightarrow -4 < 2x < 10 \Rightarrow -2 < x < 5\).
📝 Chapter Quiz
3

Functions & Graphs

🗻 Functions & Graphs 12–15%  ·  Function notation  ·  Domain & range  ·  Transformations  ·  Composition & inverse

Function notation, evaluating and composing functions, and reading the vertex of a parabola.

▲ Reference — Functions

\( f(a) \) substitutes \( a \) for \( x \); a composite \( f(g(x)) \) works inside-out. In vertex form \( y=a(x-h)^{2}+k \), the vertex is \( (h,k) \) and the axis is \( x=h \).

Slide the vertex \( (h,k) \) of \( y=(x-h)^{2}+k \). The amber dot is the vertex; the dashed line is the axis of symmetry.

⊙ Explorer · Vertex forminteractive
vertex
axis of symmetry

Moving \( h \) slides the curve left/right; \( k \) slides it up/down.

Evaluate
\( f(a) \)
Composite
\( f(g(x)) \)
Vertex form
\( a(x-h)^{2}+k \)
Rate of change
\( \dfrac{f(b)-f(a)}{b-a} \)
Worked example 3.A

If \( f(x)=x^{2}-1 \), find \( f(3) \). \[ 9-1=8. \]

Worked example 3.B

If \( f(x)=2x+1 \) and \( g(x)=x^{2} \), find \( f(g(2)) \).

\( g(2)=4 \), then \( f(4)=9 \):

\[ 9. \]

If \(f(x) = x^2 - 1\) and \(g(x) = 2x + 3\), find \(f(g(1))\).
\(g(1) = 5\). \(f(5) = 25 - 1 = 24\).
📝 Chapter Quiz
4

Coordinate Geometry

🗻 Coordinate Geometry 12–15%  ·  Slope & equations of lines  ·  Distance & midpoint  ·  Circles  ·  Parabolas

Lines in the plane: slope, intercepts, distance and midpoint, and the equations of lines.

▲ Reference — The coordinate plane

Slope \( m=\dfrac{y_2-y_1}{x_2-x_1} \); line \( y=mx+b \). Distance \( \sqrt{(x_2-x_1)^2+(y_2-y_1)^2} \); midpoint \( \left(\tfrac{x_1+x_2}{2},\tfrac{y_1+y_2}{2}\right) \).

Adjust slope \( m \) and intercept \( b \) of \( y=mx+b \); the amber dots are the intercepts.

⊙ Explorer · Slope & interceptsinteractive
slope
y-intercept
x-intercept

Parallel lines share a slope; perpendicular slopes multiply to \( -1 \).

Slope
\( \dfrac{y_2-y_1}{x_2-x_1} \)
Distance
\( \sqrt{\Delta x^{2}+\Delta y^{2}} \)
Midpoint
\( \left(\tfrac{x_1+x_2}{2},\tfrac{y_1+y_2}{2}\right) \)
Line
\( y=mx+b \)
Worked example 4.A

Find the distance between \( (0,0) \) and \( (3,4) \). \[ \sqrt{9+16}=5. \]

Worked example 4.B

Find the midpoint of \( (2,4) \) and \( (6,8) \). \[ (4,\,6). \]

What is the equation of the circle with centre \((-2, 4)\) and radius \(5\)?
\((x+2)^2 + (y-4)^2 = 25\).
📝 Chapter Quiz
5

Plane Geometry

🗻 Plane Geometry 12–15%  ·  Angles & parallel lines  ·  Triangles  ·  Polygons & circles  ·  Area & volume

Angles, triangles and polygons, circles, and area, perimeter and volume.

▲ Reference — Shapes

Triangle angles sum to \( 180^{\circ} \); a polygon of \( n \) sides sums to \( (n-2)\cdot180^{\circ} \). Pythagoras \( a^{2}+b^{2}=c^{2} \). Circle area \( \pi r^{2} \), circumference \( 2\pi r \).

Triangle area
\( \tfrac12 bh \)
Pythagoras
\( a^{2}+b^{2}=c^{2} \)
Polygon angles
\( (n-2)\cdot180^{\circ} \)
Circle
\( \pi r^{2},\ 2\pi r \)
Worked example 5.A

A right triangle has legs \( 9 \) and \( 12 \). Find the hypotenuse. \[ \sqrt{81+144}=15. \]

Worked example 5.B

Find the interior-angle sum of a pentagon. \[ (5-2)\cdot180^{\circ}=540^{\circ}. \]

A cylinder has radius 3 cm and height 8 cm. Find its total surface area.
TSA \(= 2\pi r^2 + 2\pi r h = 2\pi(9) + 2\pi(3)(8) = 18\pi + 48\pi = 66\pi \approx 207.3\) cm\(^2\).
📝 Chapter Quiz
6

Trigonometry

🗻 Trigonometry 7–10%  ·  SOH-CAH-TOA  ·  Unit circle  ·  Trig identities  ·  Graphs of trig functions

Right-triangle ratios, the values of common angles, and reading the sine curve.

▲ Reference — SOH-CAH-TOA

\( \sin\theta=\dfrac{\text{opp}}{\text{hyp}} \), \( \cos\theta=\dfrac{\text{adj}}{\text{hyp}} \), \( \tan\theta=\dfrac{\text{opp}}{\text{adj}} \). Common values: \( \sin30^{\circ}=\tfrac12 \), \( \cos60^{\circ}=\tfrac12 \), \( \tan45^{\circ}=1 \).

Slide the angle \( \theta \) along the sine curve. The readouts give \( \sin\theta \) and \( \cos\theta \).

⊙ Explorer · The sine curveinteractive
sin θ
cos θ

Sine peaks at \( 90^{\circ} \), is zero at \( 0^{\circ} \) and \( 180^{\circ} \), and bottoms at \( 270^{\circ} \).

Sine
\( \tfrac{\text{opp}}{\text{hyp}} \)
Cosine
\( \tfrac{\text{adj}}{\text{hyp}} \)
Tangent
\( \tfrac{\text{opp}}{\text{adj}} \)
Identity
\( \sin^{2}\theta+\cos^{2}\theta=1 \)
Worked example 6.A

A right triangle has opposite \( 3 \) and hypotenuse \( 5 \). Find \( \sin\theta \). \[ \sin\theta=\tfrac{3}{5}. \]

Worked example 6.B

Evaluate \( \tan45^{\circ} \). \[ 1. \]

In right triangle \(ABC\) with \(C = 90°\), \(a = 5\), \(c = 13\). Find \(\sin A\), \(\cos A\), \(\tan A\).
\(b = \sqrt{169-25} = 12\). \(\sin A = 5/13\), \(\cos A = 12/13\), \(\tan A = 5/12\).
📝 Chapter Quiz
7

Statistics & Probability

🗻 Statistics & Probability 8–12%  ·  Mean, median, mode  ·  Data spread  ·  Probability  ·  Expected value

Averages and spread, basic counting, and the probability of simple and combined events.

▲ Reference — Data & chance

Mean is total over count; the median is the middle value. Probability \( =\dfrac{\text{favourable}}{\text{total}} \); independent events multiply: \( P(A\text{ and }B)=P(A)\cdot P(B) \).

Mean
\( \dfrac{\text{sum}}{\text{count}} \)
Median
middle value
Probability
\( \dfrac{\text{fav}}{\text{total}} \)
Independent
\( P(A)\cdot P(B) \)
Worked example 7.A

Find the mean of \( 4,\,8,\,10,\,18 \). \[ \frac{40}{4}=10. \]

Worked example 7.B

A fair coin is tossed twice. Find \( P(\text{two heads}) \). \[ \tfrac12\cdot\tfrac12=\tfrac14. \]

A data set is: 4, 7, 7, 9, 12, 15. Find the mean, median, and range.
Mean \(= 54/6 = 9\). Median \(= (7+9)/2 = 8\). Range \(= 15-4 = 11\).
📝 Chapter Quiz
8

Matrices, Vectors & Complex Numbers

🗻 Advanced Topics (Matrices/Vectors/Complex) ~5%  ·  Matrix operations  ·  Vector components  ·  Complex arithmetic  ·  Polar form

The hardest ACT items touch matrices, vectors, logarithms and the imaginary unit \( i \).

▲ Reference — Advanced topics

\( i^{2}=-1 \); add matrices entrywise; a vector \( (a,b) \) has magnitude \( \sqrt{a^{2}+b^{2}} \); \( \log_b x=y \) means \( b^{y}=x \).

Imaginary
\( i^{2}=-1 \)
Matrix
add entrywise
Vector
\( \sqrt{a^{2}+b^{2}} \)
Logarithm
\( \log_b x \)
Worked example 8.A

Simplify \( i^{2}+i^{4} \). \[ -1+1=0. \]

● Complex Numbers & Polar Form

A complex number \(z = a+bi\) has modulus \(|z| = \sqrt{a^2+b^2}\) and argument \(\theta = \arctan(b/a)\). Polar form: \(z = r(\cos\theta + i\sin\theta)\). Multiplying in polar: multiply moduli, add arguments.

Worked example — Matrix determinant & inverse

Find \(A^{-1}\) for \(A = \begin{pmatrix}3&1\\5&2\end{pmatrix}\).

\(\det A = 6-5 = 1\). \(A^{-1} = \dfrac{1}{1}\begin{pmatrix}2&-1\\-5&3\end{pmatrix} = \begin{pmatrix}2&-1\\-5&3\end{pmatrix}\).

Simplify \((2+3i)(1-i)\) and write in the form \(a+bi\).
\((2+3i)(1-i) = 2 - 2i + 3i - 3i^2 = 2 + i + 3 = 5+i\).
📝 Chapter Quiz
§

Practice set

Fifty ACT-style problems spanning numbers, algebra, functions, geometry, trigonometry and statistics, tagged by difficulty. Click any problem for a full worked solution.

1

Evaluate \( 15\% \) of \( 200 \).

Basic
\[ 0.15\times200=30. \]
2

Simplify \( \dfrac{3}{4}+\dfrac{1}{8} \).

Basic

\( \tfrac{6}{8}+\tfrac{1}{8} \):

\[ \tfrac{7}{8}. \]
3

Split \( 30 \) in the ratio \( 2:3 \). Find the smaller part.

Intermediate

Five parts, each \( 6 \):

\[ 2\times6=12. \]
4

\( 12 \) is what percent of \( 48 \)?

Intermediate
\[ \frac{12}{48}=25\%. \]
5

Find the least common multiple of \( 6 \) and \( 8 \).

Intermediate
\[ \text{LCM}=24. \]
6

A recipe is scaled from 2 to 5 servings. How many cups replace \( 4 \) cups?

Intermediate

Multiply by \( \tfrac{5}{2} \):

\[ 4\times\tfrac{5}{2}=10. \]
7

A \$80 item is marked down \( 20\% \). Find the sale price.

Advanced
\[ 80\times0.80=\$64. \]
8

A car travels \( 120 \) miles in \( 3 \) hours. Find the average speed.

Intermediate
\[ \frac{120}{3}=40\ \text{mph}. \]
9

Solve \( 2x+7=19 \).

Basic

\( 2x=12 \):

\[ x=6. \]
10

Solve \( 3(x-2)=12 \).

Intermediate

\( x-2=4 \):

\[ x=6. \]
11

Factor \( x^{2}-9 \).

Intermediate
\[ (x-3)(x+3). \]
12

Solve \( x^{2}-7x+10=0 \).

Intermediate

\( (x-2)(x-5)=0 \):

\[ x=2,\ 5. \]
13

Simplify \( 2x+3x-5 \).

Intermediate
\[ 5x-5. \]
14

If \( y=2x+1 \), find \( x \) when \( y=9 \).

Intermediate

\( 2x=8 \):

\[ x=4. \]
15

Solve \( |x-3|=5 \).

Advanced

\( x-3=\pm 5 \):

\[ x=8,\ -2. \]
16

Simplify \( x^{2}\cdot x^{4} \).

Intermediate
\[ x^{6}. \]
17

Solve \( 5x-3=2x+9 \).

Intermediate

\( 3x=12 \):

\[ x=4. \]
18

Simplify \( \sqrt{50} \).

Advanced
\[ \sqrt{25\cdot2}=5\sqrt{2}. \]
19

Evaluate \( 2^{3}+3^{2} \).

Intermediate
\[ 8+9=17. \]
20

Solve the system \( x+y=7 \), \( 2x-y=2 \).

Advanced

Add: \( 3x=9\Rightarrow x=3 \), then \( y=4 \):

\[ x=3,\ y=4. \]
21

If \( f(x)=x^{2}-1 \), find \( f(3) \).

Intermediate
\[ 9-1=8. \]
22

State the vertex of \( y=(x-2)^{2}+3 \).

Intermediate
\[ (2,\,3). \]
23

If \( f(x)=2x+1 \) and \( g(x)=x^{2} \), find \( f(g(2)) \).

Advanced

\( g(2)=4 \), then \( f(4)=9 \):

\[ 9. \]
24

For what value of \( x \) is \( \dfrac{1}{x-2} \) undefined?

Intermediate

The denominator is zero:

\[ x=2. \]
25

Find the y-intercept of \( y=3x-6 \).

Intermediate
\[ (0,\,-6). \]
26

For \( f(x)=x^{2} \), find the average rate of change on \( [1,3] \).

Advanced
\[ \frac{9-1}{3-1}=4. \]
27

Find the slope of the line through \( (0,0) \) and \( (2,6) \).

Basic
\[ \frac{6}{2}=3. \]
28

Find the midpoint of \( (2,4) \) and \( (6,8) \).

Intermediate
\[ \left(\tfrac{2+6}{2},\tfrac{4+8}{2}\right)=(4,6). \]
29

Find the distance between \( (0,0) \) and \( (3,4) \).

Intermediate
\[ \sqrt{9+16}=5. \]
30

Find the slope of \( y=2x+5 \).

Intermediate
\[ m=2. \]
31

Find the x-intercept of \( 2x+3y=12 \).

Intermediate

Set \( y=0 \): \( 2x=12 \):

\[ x=6. \]
32

A line passes through \( (1,2) \) with slope \( 3 \). Find \( y \) when \( x=4 \).

Advanced

\( y-2=3(4-1) \):

\[ y=11. \]
33

Give the equation of the horizontal line through \( (0,5) \).

Intermediate
\[ y=5. \]
34

Find the area of a rectangle \( 7\times4 \).

Basic
\[ 7\times4=28. \]
35

A triangle has angles \( 50^{\circ} \) and \( 60^{\circ} \). Find the third.

Intermediate
\[ 180^{\circ}-110^{\circ}=70^{\circ}. \]
36

A right triangle has legs \( 9 \) and \( 12 \). Find the hypotenuse.

Intermediate
\[ \sqrt{81+144}=15. \]
37

Find the area of a triangle with base \( 10 \) and height \( 8 \).

Intermediate
\[ \tfrac12\times10\times8=40. \]
38

Find the area of a circle with radius \( 5 \).

Intermediate
\[ \pi(5)^{2}=25\pi. \]
39

Find the circumference of a circle with \( r=7 \). Take \( \pi=\tfrac{22}{7} \).

Intermediate
\[ 2\times\tfrac{22}{7}\times7=44. \]
40

Find the interior-angle sum of a pentagon.

Advanced
\[ (5-2)\cdot180^{\circ}=540^{\circ}. \]
41

Find the volume of a box \( 2\times3\times4 \).

Intermediate
\[ 2\times3\times4=24. \]
42

A square has area \( 36 \). Find its perimeter.

Advanced

Side \( =6 \):

\[ 4\times6=24. \]
43

A right triangle has opposite \( 3 \) and hypotenuse \( 5 \). Find \( \sin\theta \).

Intermediate
\[ \sin\theta=\tfrac{3}{5}. \]
44

Evaluate \( \sin30^{\circ} \).

Intermediate
\[ \tfrac12. \]
45

Evaluate \( \cos60^{\circ} \).

Intermediate
\[ \tfrac12. \]
46

Evaluate \( \tan45^{\circ} \).

Advanced
\[ 1. \]
47

A right triangle has adjacent \( 4 \) and hypotenuse \( 5 \). Find \( \cos\theta \).

Intermediate
\[ \cos\theta=\tfrac{4}{5}. \]
48

A right triangle has opposite \( 6 \) and adjacent \( 8 \). Find \( \tan\theta \).

Advanced
\[ \tan\theta=\tfrac{6}{8}=\tfrac{3}{4}. \]
49

Find the mean of \( 4,\,8,\,10,\,18 \).

Intermediate
\[ \frac{40}{4}=10. \]
50

A fair coin is tossed twice. Find \( P(\text{two heads}) \).

Intermediate
\[ \tfrac12\cdot\tfrac12=\tfrac14. \]

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Based on the ACT Mathematics test: 60 questions, 60 minutes, 5 answer choices, calculator permitted. Covers Pre-Algebra through Trigonometry.

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