Six Sigma Green Belt Certification Practice Exam

Given the data set 9, 3, 2, 7, 8, 2, 4, 1, 5, which measure of central tendency equals 4?

1. Mode

2. Range

3. Mean

4. Median

The correct answer is: Median

The median is the measure of central tendency that equals 4 for the given data set. To determine the median, the data must first be arranged in ascending order, resulting in the sequence: 1, 2, 2, 3, 4, 5, 7, 8, 9. The median is defined as the middle value in a sorted list of numbers. Since there are nine numbers in this dataset (an odd count), the median will be the fifth number, which is indeed 4. This characteristic of the median is particularly useful, as it is less affected by extreme values compared to the mean, providing a better representation of the central tendency in skewed distributions. In the context of the other measures mentioned: the mode refers to the most frequently occurring number in the dataset, which is 2 in this case; the range represents the difference between the maximum and minimum values, which is 9 - 1 = 8; and the mean is calculated by adding all numbers together (9 + 3 + 2 + 7 + 8 + 2 + 4 + 1 + 5 = 41) and dividing by the count of numbers (41 / 9 ≈