AFCT Arithmetic Reasoning Practice Test 2026 – Comprehensive Exam Prep

To determine the average of a set of numbers, you need to sum all the numbers and then divide by the total count of those numbers. In this case, you are looking at the numbers 10, 20, and 30.

First, you calculate the sum:

10 + 20 + 30 = 60

Next, you count the numbers in the set, which is 3 (since there are three numbers: 10, 20, and 30).

Now, to find the average, you divide the total sum by the count of the numbers:

60 ÷ 3 = 20

Therefore, the average of 10, 20, and 30 is 20. This calculation shows why the chosen answer is correct: the average reflects the central value of the numbers when they are equally distributed over the set provided.