How do you determine the median of the following data set: 3, 7, 9, 5?

To find the median of a data set, the first step is to arrange the numbers in ascending order. For the data set provided (3, 7, 9, 5), when we sort it, we get: 3, 5, 7, 9.

With an even number of observations (four in this case), the median is calculated by taking the average of the two middle numbers. In our sorted list, the two middle numbers are 5 and 7.

Thus, to find the median, we calculate the average of these two numbers: (5 + 7) / 2. This yields a median value of 6.

Choosing this option confirms the correct understanding of how to find the median in a sorted data set with an even number of elements, utilizing the two central values. The other options incorrectly reference combinations of different numbers from the set that do not represent the actual middle values based on the correct procedure for calculating the median.