In a data set, which measure is used to describe the center and can be influenced by outliers?

• A. The median
• B. The mode
• C. The mean
• D. The range

Answer: (C)

Describing a data set's center and how outliers affect that description. The mean is the measure used to describe the center that can be influenced by outliers because it averages every value. Every data point pulls the final average toward itself, so an extreme value can noticeably shift the result. For example, in the data set 1, 2, 3, 4, 100, the mean is 22, while the median is 3, showing how a single outlier drags the average upward. The median is the middle value when data are ordered and is less affected by extreme values. The mode is the most frequent value and isn’t always useful for describing center, especially if there isn’t a repeating value. The range measures spread, not center, as the difference between the largest and smallest values.