ACT · Pre-Algebra · Mean, median, mode, and range
Question act-q-00254
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The question
The five values in a data set are 19, 45, 87, 23, 27. What is the mean?
- 201
- 50.3
- 40.2
- 87
Show answer & worked solution
Answer: 40.2
Worked solution. Sum the values: 201. Divide by the number of values (5): 201 / 5 = 40.2.
Why each wrong choice is wrong. A distractor returns the median (middle value), which equals the mean only by coincidence. Another divides by the wrong count.
Test-day tactic. Mean is sum over count. Don't confuse it with median (middle value) or mode (most frequent value).
About this question type
Items test mean, median, mode, and range on small data sets, often asking how a single added or changed value affects each.
You will see a question shaped like this one on roughly every other official ACT form, typically at an early position in the section, where missing them carries an outsize penalty because the curve assumes everyone in your band gets them right. Treat any miss in this subtopic as a signal to drill the subtopic page before you do another full practice test.