For a finite numerical data set, the mean is the total divided by the number of values and represents an equal-share balance point; the median is the middle value when data are ordered (or the mean of the two middle values), the mode is the most frequent value and may be absent or nonunique, and the range is maximum minus minimum. Interpretation includes comparing how these measures describe center and spread and recognizing that extreme values affect the mean and range more than the median. This scope excludes weighted means, grouped-data estimates, and inferential statistics.
For a data set, use these steps:
A group of students records the number of minutes they read:
The data are already in order.
1. Find the mean
Add the values:
There are values, so divide by :
The mean reading time is about minutes.
2. Find the median
There are values, so there are two middle values: and .
Find their mean:
The median is minutes.
3. Find the mode
The value occurs twice, while every other value occurs once.
4. Find the range
Subtract the smallest value from the largest value:
The range is minutes.
The mean and median describe the center of the data. The mode shows the most common value, and the range describes the spread from the smallest to the largest value. An unusually large or small value affects the mean and range more than it affects the median. Here, the value increases the mean and the range, but the median is less affected.
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