Find the median of the following set of numbers: 3, 7, 9, 5, 12.

To find the median of a set of numbers, the first step is to arrange the numbers in ascending order. For the set 3, 7, 9, 5, 12, when we rearrange them, we get: 3, 5, 7, 9, 12.

Next, since there are five numbers in this set (which is an odd number), the median will be the middle number. In this case, when counting to find the middle number, the third position in the ordered list corresponds to the median.

The ordered set is:

1. 3

2. 5

3. 7

4. 9

5. 12

The third number is 7. Therefore, the median of the set is 7, making it the correct answer. Finding the median this way ensures that we accurately determine the center value of the data set.