The following are the changes made to the Official ACT Prep Guide 20202021 that was released in April 2020.

Test 1 (Form 20MC6) is a new test and is a copy of 2018 June ACT (Form code A11).

Test 2 (Form 16MC1): This practice test is a copy of the first practice test from last year’s official guide. The math section of this test has 40 questions from the June 2015 ACT test (Form 73C), and the remainder are questions taken from the five tests in the old Real ACT Guide.

Test 3 (Form 16MC2): This practice test is a copy of the second practice test from last year’s official guide. Half of the math questions are from taken from Test#2 in the Real ACT guide and the remainder are from the other tests in the Real ACT guide.

Test 4 (Form 18MC4). This practice test is identical to the Test 4 in last year’s guide, and a duplicate of 2017 June ACT test (Form 74C).

Test 5 (Form 19MC5): This practice test is identical to the Test 5 in last year’s guide, and a duplicate of 2017 December ACT test (Form A10 or 75E).
My recommendation is to skip buying this guide, and instead directly practice with the five original official tests: 2018 June ACT(Form A11), 2015 April ACT(Form 73G), 2015 June ACT(Form 73C), 2017 June ACT(Form 74C), and 2017 December ACT(Form A10). I do not recommend buying this guide.
Vee says
Can you please confirm as I think there is one error?
Practice Test 1 Science Test Q19
% error formula should be
absolute value of [(actual value – expected value)*100] / expected value
But in the book they say [(experimental value – actual value)*100] / actual value
Dabral says
The answer to question 19 in science is indeed A. The percent error is relative to the actual value, meaning how much does the experimental value deviates from the actual value. So the percent error would be Experimental value – Actual Value*100/Actual Value, which is what is written in the book.