ACT Math · Pre-Algebra
Mean, median, mode, and range
Measures of center and spread on small data sets.
What's tested in this subtopic
Items test mean, median, mode, and range on small data sets, often asking how a single added or changed value affects each.
Tactics that actually move your score
Compute mean, median, and mode separately — they are not interchangeable. Mode can have multiple values or none. The single biggest leverage point on most subtopics isn't learning more math — it's recognizing the test's preferred surface forms quickly enough that you don't burn 30 seconds re-reading the question. The first time you see a particular phrasing it might take you a full minute. The tenth time you see it, you should be reaching for your method before you've finished the sentence. Repetition is what builds that recognition. Fifteen problems in a row of the same shape is more useful than fifty mixed.
Practice questions (14)
- Easy The five values in a data set are 82, 46, 30, 33, 85. What is the mean?
- Easy The five values in a data set are 19, 45, 87, 23, 27. What is the mean?
- Medium The five values in a data set are 76, 69, 77, 49, 26. What is the mean?
- Medium The five values in a data set are 60, 82, 53, 35, 31. What is the mean?
- Medium The five values in a data set are 58, 31, 59, 78, 67. What is the mean?
- Hard The five values in a data set are 64, 66, 58, 54, 34. What is the mean?
- Easy The five values in a data set are 15, 74, 61, 82, 15. What is the mean?
- Easy The five values in a data set are 88, 63, 49, 37, 71. What is the mean?
- Medium The five values in a data set are 70, 82, 90, 43, 56. What is the mean?
- Medium The five values in a data set are 88, 78, 89, 31, 67. What is the mean?
- Medium The five values in a data set are 42, 11, 45, 24, 34. What is the mean?
- Hard The five values in a data set are 27, 39, 68, 32, 64. What is the mean?
- Easy The five values in a data set are 26, 43, 81, 35, 14. What is the mean?
- Easy The five values in a data set are 84, 81, 27, 41, 24. What is the mean?
How to drill
Work through the questions above untimed. After each one, read the worked solution from start to finish — even when you got it right. Note which solution method you used, and which method we used; if they differ, ask yourself which would have been faster on test day. Speed in ACT math comes from shortening your method-selection step, not from doing arithmetic faster. Most fast students are doing the same arithmetic everyone else is — they're just spending less time deciding what to do.
Once you can clear the easy and medium items in this subtopic at 90% accuracy, attempt a timed mini-set of ten hard items at 75 seconds each. If you finish in time and score 7+ correct, you've effectively mastered the subtopic for test purposes and can move on.