What is the mean of a data set?

• A. The sum of all values divided by the number of values
• B. The middle value when data are arranged in order
• C. The range of the data
• D. The value that occurs most often

Answer: (A)

The mean is the arithmetic average of a data set. You add up all the values and then divide by how many values there are. This gives a single representative value that reflects every data point. For example, with values 2, 4, and 6, the sum is 12 and there are 3 values, so the mean is 12 ÷ 3 = 4. The mean uses every number in the set, so unusually small or large values can pull it toward them.

Other options describe different measures: the median is the middle value when the data are ordered; the range is the difference between the largest and smallest values; the mode is the value that occurs most often. These are distinct ways to describe center or spread.