How is the mean of a data set defined?

The mean of a data set is defined as the average of a set of numbers, which is calculated by summing all the values in the data set and then dividing that sum by the total number of values. This process provides a measure of central tendency that reflects the overall level of the data.

For instance, if you have a data set of scores like 4, 5, 6, and 7, you first add these numbers together to get a total of 22. Then, dividing by the count of numbers, which is 4 in this case, you find the mean is 5.5. This value represents the center point of the scores, providing useful information about the data set as a whole.

The other options describe different concepts: the middle value refers to the median, the most frequently occurring value describes the mode, and the difference between the highest and lowest values refers to the range. These are all measures of central tendency or variability but do not define the mean.