Range and Mean
Lesson
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Range is the difference between the greatest and the least numbers in a set of data.

Step 1: First arrange data in order starting with the least number. 
Step 2: The greatest value minus the least value is the range.

 Example 1:Find the Range

Each x on the line plot stands for one student. 

0 = least number

Books students read in one month.

5 = greatest number

The range is the difference between the least and the greatest number.
5 - 0 = 5 Range = 5

 

Example 2: Find the Range

Suppose these are the distances you rode your bike for one week.

 

In a list of data, the difference between the least and the greatest is the range.

3, 4, 4, 5, 6, 8, 8

3 = least number
8 = greatest number

8 - 3 = 5 Range = 5

The mean (or average), is one way to find a number that best represents all the numbers in a set.

Step 1: Find the sum.
Step 2: Divide the sum by the number of addends.

Example

Phil's math grades for one week.

95 90 85 80 70
   
Suppose Phil's five math grades are 95, 90, 85, 80, 70.  To find out his average grade, follow these steps.
Step 1: Find the sum of the grades.
95 + 90 + 85 + 80 + 70 = 420
Step 2: Divide the sum by the number of grades.
420  5 = 84
 


Remember: Finding Range
First arrange data in order starting with the least number. 
The greatest value minus the least value is the
range.
 

Remember: Finding Mean or Average (both words are interchangeable)
Step 1    Add the numbers.
Step 2   Count the number of addends.
Step 3   Divide the sum by the number of addends.

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