What is the median of the following set of numbers: 5, 8, 12, 15, 20?

To find the median of a set of numbers, you first need to arrange the numbers in ascending order, and then identify the middle value. In this case, the numbers provided are already in order: 5, 8, 12, 15, 20.

The median is the value that separates the higher half from the lower half of the data set. Since there are five numbers in this set, which is an odd amount, the median is simply the middle number. In this ordered list, the third number is 12, which is centrally located among the five numbers.

When you determine the median, it reflects the point at which half of the numbers are above and half are below this value. In this situation, there are two numbers (5 and 8) below 12 and two numbers (15 and 20) above it, verifying that 12 indeed divides the set into two equal parts.

Thus, the correct answer is 12, as it accurately represents the median of the given set of numbers.