What Letter Should I Guess on the ACT?

The timed nature of the ACT can make finishing the test without rushing very challenging.  This results in many students guessing on the last few questions in each section. But is there a better way to guess than guessing randomly?


The common theory is “when in doubt, pick C/H.”  But does this offer an advantage over the other letters?

The short answer is no…at least not for English, Reading, and Science. 

The ACT does a computer randomization for most of their answer choices to ensure that answer choices are evenly distributed.  Because of this, the best choice is to choose the same letter in a straight line.  This will average 25% correct (20% correct for Math) and will capitalize on the even distribution better and more consistently than random guessing.  So, guessing C/H straight down is technically better than guessing randomly, but the same is true for any letter.

However, there is an exception: the Math section.  When we crunched the numbers, a surprising trend emerged in the answer choices at the end of the Math section.


The Math section is designed to roughly increase in difficulty and complexity from beginning to end.  This means the hardest and most time-consuming questions tend to be at the end.  We often recommend to students with time issues to focus on the quality of the first 40-50 questions and “cherry pick” questions at the end they think they can complete with the time remaining.  Guessing on the last 10 in Math can be beneficial for students who have difficulty finishing this section because the time spent on one time-consuming question at the end would be better served carefully and correctly answering multiple questions in the beginning.

The ACT knows, of course, that many students do not finish the Math section.  In our analysis of released ACT tests going back to 2012, it appears that the ACT is actively avoiding B/G and C/H as answer choices in the last 10 on the Math section.  Because those letters are the most commonly guessed answers, they avoid these letters to ensure that guessing doesn’t disproportionately inflate students’ scores.   

Our data shows that instead of B/G and C/H being correct 20% of the time on the last 10 of Math, as would be statistically expected, B/G was the correct answer only 15% of the time and C/H was correct a mere 12% of the time.  That is almost half as much as would be expected!


While the probability of each letter should average to 20%, we found that A/F was correct 25% of the time while E/K was correct 24% of the time.  But picking the better letter for the last ten of Math depends on how much you wish to gamble:

  • The Gamble: Answer choice A/F was found to be a high risk/high reward option.  There is a roughly equal probability that A/F could result in 40% or more correct or 10% or less.  This boom or bust may be appealing to some and wildly inconsistent for others. For those guessing on only a few of the last ten questions, A/F would be the better option.
  • The Safe Bet: Answer choice E/K is the safest choice because it, so far, has always had one correct answer.  In fact, E/K has met or exceeded the expected average 82% of the time, making it the most consistent answer choice.  The only negative is that, compared to A/F, it has a much lower probability of scoring 40% or more correct.


It may not seem like much:  we found a pattern in ten of the 215 questions on the ACT.  But having a statistically better letter like A/F or E/K and absolutely avoiding B/G and C/H in the last ten of the Math section could raise the overall Math score by 1 or even 2 points.  If the composite score is on the borderline, like a 29.25 composite rounded down to a 29, then just one more point in any section would push that composite up to a 29.5 and round up to a 30.  So optimal guessing can be very significant.

To summarize:

  • If you are guessing on the English, Reading, and Science, it doesn’t matter what you guess, but you should guess in a straight line.
  • On the Math section, if you are guessing in the last 10, A/F or E/K is the better guess.

A lot of little improvements can add up to a massive advantage. This is one more small improvement to help you perform better on test day, reach your potential, and succeed in life.

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