This page contains a list of typos or errors from my books. If you think you've found an error, please let me know through the contact page. The edits will be incorporated in future editions.

#### SAT Math: Advanced Guide and Workbook

The following errors appear only in the 2nd edition of the book (published in 2020). We recommend purchasing the 3rd edition of the book for the Digital SAT (published in 2024).

**Chapter 3 Exponential vs. Linear Growth (pg. 26)**: The linear decay example equation should be \(A = 100 - 5t\).

**Chapter 22 Triangles, Example 8 (pg. 196)**: In the sentence that reads "\(AD\) is then \(\dfrac{2}{3}\times 7.5 = \boxed{5}\)" in the answer explanation, \(AD\) should be \(AP\).

**Chapter 28 Statistics II, Example 3 Part 2 (pg. 256)**: Answer choice C should say *"90 beats per minute"* instead of *"0 beats per minute"*.

The following errors appear only in the 1st edition of the book (published in 2015). They have been fixed in the 2nd edition (published in 2020).

**Chapter 3 Exponential vs. Linear Growth, #3 (pg. 26)**: The answer explanation on page 260 has a typo. The rate should be \(1 - 0.06 = 0.94\).

**Chapter 7 Constructing Models, #1 (pg. 47)**: The question should read *"... and then lays \(\dfrac{x}{2}\) bricks per hour for \(2y\) more hours."*

**Chapter 21 Triangles, #14 (pg. 184)**:The diagram is drawn incorrectly, though it's hard to tell. The diagram should be drawn so that triangle \(ABC\) is similar to triangle \(DEF\) (and the sides should correspond).

**Chapter 23 Trigonometry, #12 (pg. 207)**: The answer explanation on page 310 has a typo. In quadrant III, sine and cosine are both **negative** (not positive).

**Chapter 25 Probability, #10 (pg. 223)**: The first sentence of the question should read *"A manufacturer uses two assembly lines to produce refrigerators."*

**Chapter 26 Statistics I, #13 (pg. 234)**: The given answer and explanation are incorrect. There is no correct answer. The mean value of school B is actually greater than the mean of school A (3.67 vs. 3.42). This question has been revised in the 2nd edition.

#### SAT Writing: Advanced Guide and Workbook

**Chapter 8 Run-ons, Exercise 1, #4 (pg. 39)**: There should be a comma after *"apparently"*.

**Chapter 16 Commas, Dashes, & Colons, Example 4 (pg. 86)**: Both sentences are labeled as "Wrong". The second sentence should be labeled as "Correct".

The following errors have been fixed for all official copies purchased after July 19th, 2020. In addition, a handful of words were revised purely for "cosmetic" purposes.

**Chapter 6 Subject Verb Agreement, Exercise 3, #3 (pg. 26)**: This question needs to be revised as the answer is unclear. "A variety" can take a singular or plural verb depending on the context and the emphasis. For this question, the answer could be either singular or plural. The good news is that the SAT won't test you on this distinction.

**Chapter 15 Tenses, Exercise 3, #3 (pg. 83)**: Answers A and B are both possible. This question needs to be revised to be more clear-cut.

**Chapter 16 Commas, Dashes, & Colons, Exercise 1, #19 (pg. 96)**: Answers A and D are both possible. This question needs to be revised to be more clear-cut.

**Chapter 18 Word Choice, Example 6 (pg. 108)**: The "to" in the question's sentence should not be underlined.

**Chapter 23 Placement, Example under Supporting Sentences (pg. 164)**: Answers C and D are both possible. This example needs to be reworked so that there is a clear answer.

**Chapter 26 Combining Sentences, Exercise 1, #10 (pg. 183)**: Answers A and C are both possible, though answer A is preferable since it doesn't introduce a whole new independent clause.

#### SAT Math: 10 Practice Tests

The following errors have been fixed for all official copies purchased after Feb 22nd, 2020. In addition, a few questions have been revised or replaced to adhere to the current state of the SAT exam: Test 1 Section 4, #24 and #25; Test 2 Section 3, #13; Test 4 Section 3, #10; and Test 7 Section 4, #13 and #18. You can view the updated questions here. Despite the changes, page numbers have been kept the same for all practice tests in the book. Also note that many questions have been recategorized to stay up-to-date with chapters in the 2nd edition of the SAT Math Advanced Guide and Workbook.

**Practice Test 1, Section 3, #2**: The answer is correct but here's the correct explanation: \(\dfrac{\dfrac{1}{x}}{x + 3} = \dfrac{1}{x}\div (x + 3) = \dfrac{1}{x}\times\dfrac{1}{x + 3} = \dfrac{1}{x(x + 3)}\)

**Practice Test 1, Section 3, #3**: The answer is correct but here's the correct explanation: The equation is satisfied only when \(x = 2, y = 3\), and \(z = -4\). So, \(x + y + z = 2 + 3 + (-4) = \boxed{1}\).

**Practice Test 1, Section 4, #25**: This question needs to be revised because it is a bit too subtle to be a realistic SAT question. It's too easy to arrive at different answers depending on which points are tested.

**Practice Test 2, Section 3, #19**: The question should read *the expression above is equivalent to \(\dfrac{k}{x(x - 3)^2}\)* (NOT \(\dfrac{k}{(x - 3)^2}\))

#### ACT Math: Advanced Guide and Workbook

**Chapter 16 Triangles, Example 6 (pg. 110)**: The figure is drawn incorrectly. Triangles \(ABC\) and \(DEF\) are similar, but there is a mismatch of corresponding sides in the figure.

The following errors have been fixed for all official copies purchased after Feb. 10th, 2020.

**Chapter 1 Absolute Value, #7 (pg. 8)**: The correct answer is C, not E.

**Chapter 6 Properties of Numbers, Example 6 (pg. 35)**: The correct answer should be \(\dfrac{3}{25} = 12\%\), since only 3 numbers (10, 32, and 54) are even.

#### ACT English: Hardcore ACT Prep

The following errors have been fixed for all official copies purchased after July 10th, 2023. In addition, a handful of questions were rewritten for "cosmetic" purposes.

**Chapter 8 Modifiers, Exercise 2, #9 (pg. 44)**: Answer C could also be correct if the underlined portion is separated off with commas. This question will be revised in future updates to the book.

**Practice Test 1, #43 (pg. 228)**: Answer A is not wrong. The answer explanation (pg. 239) has a typo. It should read *"Answer B is wrong because it separates..."*