What is the median of the following set of numbers: 3, 7, 9, 5, 12?

• A. 7
• B. 9
• C. 10
• D. 12

Answer: (A)

To find the median of a set of numbers, you begin by arranging the numbers in ascending order. For the given set of numbers: 3, 7, 9, 5, and 12, when arranged, they become: 3, 5, 7, 9, 12.

The median is the middle number in this ordered list. In this case, there are five numbers, which is an odd count. The middle number is the third number in this sequence, since it’s positioned between the lower and upper halves of the data set.

Counting from the left side, the first number is 3, the second is 5, and the third number is 7. Therefore, the median of this set is indeed 7, which corresponds to the correct answer.

Understanding this concept is crucial because the median is a measure of central tendency that gives us insight into the data, especially when the set contains an odd number of observations.