mathematics practice
Overview
This page contains 25 practice problems organised by the four content domains of the SAT Mathematics section. Each problem includes a step-by-step solution, the key concept tested, and common mistakes to avoid. These problems span the difficulty range you will encounter on the digital SAT, from straightforward applications to multi-step problems requiring careful reasoning.
Algebra
Problem 1: Linear Equations
If , what is the value of ?
Solution:
Key concept: Solving a linear equation by distributing, combining like terms, and isolating the variable.
Common mistakes:
- Forgetting to distribute the 3 to both terms in
- Dropping the negative sign when moving to the right side
- Arithmetic errors in
Problem 2: Systems of Equations
A store sells notebooks for $3 each and pens for $2 each. If a customer buys 14 items and spends $34 in total, how many notebooks did the customer buy?
Solution:
Let = number of notebooks and = number of pens.
From the first equation: .
Substitute into the second:
The customer bought 6 notebooks.
Key concept: Solving a system of linear equations using substitution.
Common mistakes:
- Setting up the equations with incorrect coefficients (confusing which item costs $3 and which costs $2)
- Solving for but answering with instead
- Forgetting to verify: ✓
Problem 3: Linear Functions
A line passes through the points and . What is the equation of this line in slope-intercept form?
Solution:
Using point-slope form with point :
The equation is .
Key concept: Calculating slope from two points and writing the equation in slope-intercept form.
Common mistakes:
- Reversing the order of subtraction in the slope formula (getting gives the same result, but inconsistent order can lead to sign errors)
- Making arithmetic errors when substituting into point-slope form
- Forgetting to simplify the final equation
Problem 4: Inequalities
Solve the inequality . Express the solution as an inequality.
Solution:
Dividing by (reverse the inequality sign):
Key concept: Solving a linear inequality, remembering to reverse the inequality sign when dividing by a negative number.
Common mistakes:
- Forgetting to reverse the inequality sign when dividing by
- Sign errors when distributing to both terms
- Writing incorrectly (it simplifies to , not )
Problem 5: Absolute Value
What is the sum of all integer solutions to ?
Solution:
Add 3:
Divide by 2:
The integer solutions are .
Sum:
Key concept: Solving an absolute value inequality by rewriting as a compound inequality.
Common mistakes:
- Writing only (forgetting the negative case)
- Incorrectly dividing: dividing by a positive number (2) does not require reversing the inequality
- Off-by-one errors when listing integer solutions (including 6 or excluding )
Problem 6: Linear Word Problem
A tank initially contains 200 litres of water. Water is added at a constant rate of 15 litres per minute. At the same time, water drains from a leak at a constant rate of 3 litres per minute. How many minutes will it take for the tank to contain 380 litres?
Solution:
Net rate of change: litres per minute.
Amount needed: litres.
It takes 15 minutes.
Key concept: Modelling a real-world scenario with a linear equation using rate of change.
Common mistakes:
- Forgetting to account for the leak (using 15 litres/min instead of the net 12 litres/min)
- Using the initial amount instead of the difference ()
- Arithmetic errors in
Advanced Math
Problem 7: Quadratic Equations
What are the solutions to ?
Solution:
Factor: find two numbers that multiply to and add to .
The numbers are and .
The solutions are and .
Key concept: Factoring a quadratic by splitting the middle term (AC method).
Common mistakes:
- Incorrect factor pair (e.g., and multiply to but add to , not )
- Sign errors during grouping
- Forgetting that gives , not
Problem 8: Polynomial Operations
If and , what is the remainder when is divided by ?
Solution:
By the Remainder Theorem, the remainder is :
The remainder is 31.
Key concept: The Remainder Theorem — the remainder of equals .
Common mistakes:
- Evaluating instead of (the theorem applies to , so , not )
- Arithmetic errors in computing or
- Attempting full polynomial long division (correct but slower and more error-prone)
Problem 9: Exponential Functions
A population of bacteria doubles every 3 hours. If the initial population is 500, which expression gives the population after hours?
A)
B)
C)
D)
Solution:
The population doubles every 3 hours. After hours, the number of doubling periods is .
Correct answer: C
Key concept: Writing exponential growth functions from a doubling time.
Common mistakes:
- Choosing A, which is linear growth, not exponential
- Choosing B, which confuses the exponent (doubling 3 times per period instead of once every 3 hours)
- Choosing D, which swaps the base and the exponent coefficient
Problem 10: Function Composition
If and , what is ?
Solution:
First evaluate :
Then evaluate at this result:
Key concept: Function composition — evaluating the inner function first, then using its output as the input to the outer function.
Common mistakes:
- Evaluating first instead of (computing instead of )
- Arithmetic errors: , not
- Forgetting to apply to the result of
Problem 11: Nonlinear Equations
If and , what is the value of ?
Solution:
From , square both sides:
Substitute :
Key concept: Using the identity to solve a system of equations without finding and individually.
Common mistakes:
- Attempting to solve for and individually (possible but more time-consuming)
- Forgetting the middle term when expanding
- Dividing 24 by 2 incorrectly
Problem 12: Rational Equations
If , what is the value of ?
Solution:
Multiply through by the common denominator, 15:
Key concept: Solving a rational equation by clearing denominators.
Common mistakes:
- Incorrect common denominator (the LCD of 3 and 5 is 15)
- Sign errors when distributing: , not
- Arithmetic errors in
Problem 13: Quadratic in Vertex Form
The function is rewritten in the form . What is the value of ?
Solution:
Complete the square:
So and .
Key concept: Converting a quadratic from standard form to vertex form by completing the square.
Common mistakes:
- Incorrectly completing the square: , so you must subtract 16 to keep the expression equivalent
- Finding and correctly but making a sign error in the sum
- Using instead of (forgetting that the vertex form is , so is half of )
Problem Solving and Data Analysis
Problem 14: Ratios and Percentages
A shirt originally priced at $80 is discounted by 25%. An additional 10% discount is then applied to the sale price. What is the final price of the shirt?
Solution:
After the first discount:
After the second discount:
The final price is $54.
Key concept: Successive percentage changes multiply rather than add.
Common mistakes:
- Adding the percentages: and computing (incorrect)
- Applying the second discount to the original price: and subtracting from $60 to get $52 (still wrong — successive discounts multiply)
- Correct approach: each discount applies to the current price, not the original
Problem 15: Unit Conversions
A car’s fuel efficiency is 12 kilometres per litre. If petrol costs $1.45 per litre, what is the approximate cost per kilometre to drive this car? (Round to the nearest cent.)
Solution:
Cost per kilometre = (cost per litre) ÷ (kilometres per litre)
Rounded to the nearest cent: approximately $0.12 per kilometre.
Key concept: Using unit rates and dimensional analysis to convert between related quantities.
Common mistakes:
- Multiplying instead of dividing (getting $17.40 per kilometre, which is clearly unreasonable)
- Incorrect rounding (0.1208 rounds to 0.12, not 0.13)
- Forgetting to divide by 12 (using $1.45 per kilometre)
Problem 16: Scatter Plots and Line of Best Fit
A set of data has a least-squares regression line , where represents years of experience and represents predicted annual salary (in thousands of dollars). What is the predicted salary for someone with 8 years of experience?
Solution:
Since is in thousands of dollars, the predicted salary is \27,100$.
Key concept: Using a regression equation to make predictions. The slope (3.2) means salary increases by approximately $3,200 per additional year of experience.
Common mistakes:
- Forgetting that is in thousands (answering $27.1 or $271 instead of $27,100)
- Incorrect computation: , not
- Confusing the slope and y-intercept
Problem 17: Probability
A bag contains 4 red marbles, 6 blue marbles, and 5 green marbles. Two marbles are drawn at random without replacement. What is the probability that both marbles are blue?
Solution:
Total marbles: .
Probability the first is blue: .
After removing one blue marble, 14 marbles remain, 5 of which are blue.
Probability the second is blue: .
Key concept: Probability of dependent events (without replacement). Multiply the conditional probabilities.
Common mistakes:
- Using replacement: (incorrect)
- Not reducing before multiplying, leading to (same answer but more error-prone)
- Forgetting that “without replacement” changes the denominator and numerator for the second draw
Problem 18: Statistics
The five numbers have a mean of 10. What is the value of ?
Solution:
Key concept: The mean is the sum of values divided by the count. Use the given mean to find the missing value.
Common mistakes:
- Addition errors in (it equals 36)
- Multiplying incorrectly
- Placing in the wrong position when computing the median instead (the question asks for the mean)
Problem 19: Statistics — IQR
A dataset has the following five-number summary: minimum = 12, , median = 24, , maximum = 45. What is the interquartile range (IQR)?
Solution:
Key concept: The interquartile range measures the spread of the middle 50% of data.
Common mistakes:
- Using maximum minus minimum (), which is the range, not the IQR
- Using median minus (), which is only half the IQR
- Confusing and and computing (IQR is always non-negative)
Problem 20: Two-Way Tables
A survey of 200 students found the following distribution:
| Prefers Science | Prefers Literature | Total | |
|---|---|---|---|
| Year 10 | 40 | 60 | 100 |
| Year 11 | 50 | 50 | 100 |
| Total | 90 | 110 | 200 |
What fraction of the Year 10 students prefer Science?
Solution:
Year 10 total = 100. Year 10 students who prefer Science = 40.
Key concept: Reading a two-way table and computing a conditional probability/fraction from a specific row.
Common mistakes:
- Using the total Science count: (this is the fraction of Science-preferring students who are in Year 10, not the question asked)
- Using the total of all students:
- Confusing rows and columns
Geometry and Trigonometry
Problem 21: Area of Composite Shapes
A rectangle has length 12 and width 8. A semicircle is constructed on one of the longer sides as its diameter. What is the total area of the composite shape? (Use .)
Solution:
Area of rectangle: .
The semicircle has diameter 12, so radius .
Area of semicircle: .
Total area: .
Key concept: Decomposing a composite shape into familiar figures and summing their areas.
Common mistakes:
- Using diameter instead of radius (, not )
- Forgetting the factor for a semicircle
- Using the shorter side (8) as the diameter instead of the longer side (12)
Problem 22: Circle Theorems
A circle has centre . Points , , and lie on the circle such that angle . What is the measure of angle ?
Solution:
Angle is a central angle. The arc has measure .
Angle is an inscribed angle that subtends the same arc .
An inscribed angle is half the measure of its intercepted arc:
Key concept: The Inscribed Angle Theorem — an inscribed angle is half the central angle that subtends the same arc.
Common mistakes:
- Assuming the inscribed angle equals the central angle (answering )
- Dividing by the wrong number or misidentifying which arc is subtended
- Confusing inscribed and central angles when the vertex is on vs. at the centre
Problem 23: Angle Relationships
Two parallel lines are cut by a transversal. One of the eight angles formed measures . What is the measure of an angle adjacent to this one?
Solution:
Adjacent angles formed by intersecting lines are supplementary (they sum to ).
The adjacent angle measures .
Key concept: Linear pairs formed by intersecting lines are supplementary.
Common mistakes:
- Assuming adjacent angles are equal (confusing with vertical angles, which are equal)
- Selecting without recognising the question asks for the adjacent angle
- Forgetting that this applies regardless of whether the lines are parallel (adjacent angles are always supplementary)
Problem 24: Right Triangle Trigonometry
In right triangle with right angle at , the hypotenuse and leg . What is ?
Solution:
First find using the Pythagorean theorem:
For angle : opposite side is , hypotenuse is .
Key concept: Applying SOH CAH TOA and the Pythagorean theorem in a right triangle.
Common mistakes:
- Using (adjacent) instead of (opposite) for
- Computing instead of
- Confusing which angle is (the angle at vertex , not at )
Problem 25: Similar Triangles
Triangle is similar to triangle with a scale factor of (every length in is of the corresponding length in ). If the area of is 24 square units, what is the area of ?
Solution:
The ratio of areas of similar figures equals the square of the ratio of corresponding lengths.
The area of is 54 square units.
Key concept: The area ratio of similar figures is the square of the length ratio.
Common mistakes:
- Using the length ratio directly () instead of squaring it
- Squaring the wrong ratio ( vs. )
- Setting up the proportion inverted:
Problem 26: Volume and Surface Area
A right circular cylinder has radius 5 cm and height 12 cm. What is the total surface area of the cylinder? (Use .)
Solution:
Total surface area = lateral area areas of two bases.
Lateral area:
Area of each base:
Total: cm².
Key concept: Surface area of a cylinder = .
Common mistakes:
- Forgetting to include both circular bases (omitting the factor of 2 on )
- Using the diameter (10) instead of the radius (5)
- Computing volume () instead of surface area
Problem 27: Similar Triangles and Midsegments
In triangle , point is the midpoint of and point is the midpoint of . If , what is the length of ?
Solution:
The segment connecting the midpoints of two sides of a triangle (the midsegment) is parallel to the third side and half its length.
Key concept: The Triangle Midsegment Theorem.
Common mistakes:
- Assuming (it is half, not equal)
- Assuming
- Confusing which side is parallel to ( since and are midpoints of the other two sides)
Problem 28: Angle Relationships in Polygons
What is the sum of the interior angles of a regular octagon?
Solution:
Sum of interior angles of an -sided polygon:
For an octagon ():
Each interior angle of a regular octagon: .
Key concept: The polygon interior angle sum formula.
Common mistakes:
- Using (incorrect formula)
- Using (incorrect formula)
- Confusing interior and exterior angles (exterior angle sum is always )
Problem 29: Right Triangle Trigonometry — Application
A ladder leans against a wall, making a angle with the ground. If the foot of the ladder is 4 feet from the base of the wall, how long is the ladder?
Solution:
The ground, wall, and ladder form a right triangle. The ladder is the hypotenuse.
The distance from the wall (4 ft) is the side adjacent to the angle.
The ladder is approximately 13 feet long.
Key concept: Choosing the correct trigonometric ratio based on which sides are known. Since we know the adjacent side and want the hypotenuse, we use cosine.
Common mistakes:
- Using or instead of (identifying the wrong sides)
- Computing incorrectly
- Placing 4 in the numerator without the cosine function: (this would be the distance from the wall to the top of the ladder, not the ladder length)
Problem 30: Circle Equation
A circle has the equation . What is the radius of this circle?
Solution:
Complete the square for both and .
Group terms and terms, move the constant:
Complete the square for : (add 9 to both sides)
Complete the square for : (add 16 to both sides)
This gives centre and radius .
Key concept: Converting the expanded form of a circle equation to standard form by completing the square.
Common mistakes:
- Sign errors when completing the square: requires adding , giving
- Forgetting to add the same constants to the right side of the equation
- Taking the square root of 36 incorrectly, or confusing radius with diameter
Summary
| Domain | Problems | Key Topics |
|---|---|---|
| Algebra | 1-6 | Linear equations, systems, inequalities, absolute value |
| Advanced Math | 7-13 | Quadratics, polynomials, exponentials, function composition, rational equations |
| Problem Solving and Data Analysis | 14-20 | Percentages, unit conversions, regression, probability, statistics, two-way tables |
| Geometry and Trigonometry | 21-30 | Composite areas, circle theorems, similar triangles, trigonometry, volume, polygon angles |
The most effective approach to these problems is:
- Identify the concept before reaching for a formula.
- Write out every step — the SAT rewards accuracy over speed.
- Check your answer by substituting back or estimating whether the result is reasonable.
- Review the common mistakes for each problem type — most errors fall into predictable patterns.
Worked Examples
Worked examples demonstrating the application of key concepts are covered in the detailed sub-pages linked above.
Common Pitfalls
- Confusing terminology or concepts that appear similar but have distinct meanings.
- Overlooking key assumptions or boundary conditions that limit applicability.