1. 7th Grade Math
Mean, Median, and Range
Obj. 5b

2. Central Tendency Mean Median Set of Numbers: 2, 3, 1, 1, 0, 1, 2, 4
When you have a “set of data” (or numbers), there are 2 different
ways you can find the center of the data.
Mean
Median
Let’s look at these 2 different ways to find the center using the following…
Set of Numbers: 2, 3, 1, 1, 0, 1, 2, 4

3. Mean
Mean = Average

4. Divide by the # of items in the dataset.
What is the Mean?
Your report card has an average on it.
The Mean is the average.
2 simple steps will give you the mean of a set of numbers.
Mean = Average
Step 1
Add the numbers.
Step 2
Divide by the # of items in the dataset.

5. Divide by the # of items in the dataset.
Example of Mean:
Step 1
Add the numbers.
Step 2
Divide by the # of items in the dataset.
Set of Numbers: 2, 3, 1, 1, 0, 1, 2, 4
Add the numbers: =
Divide by total items: 14 ÷ 8 =
Mean 14
1.75

6. Median
Median = Middle

7. What is the Median? The Median is the middle number.
How do you find the Median?
Median = Middle
If there is just 1 middle #:
your done!
ORDER
the numbers.
FIND
the middle #.
If there are 2 middle #’s
Average the 2 middle numbers.

8. Example of Median Median Set of Numbers: 2, 3, 1, 1, 0, 1, 2, 4
ORDER
the numbers.
If there is just 1 middle #:
your done!
If there are 2 middle #’s
FIND
the middle #.
Average the 2 middle numbers.
Add the 2 middle numbers
Then, Divide by 2
Set of Numbers: 2, 3, 1, 1, 0, 1, 2, 4
Arrange in order: 0, 1, 1, 1, 2, 2, 3, 4
= 3
3 ÷ 2 =
1.5
Median

9. Range
Range = Biggest – Smallest

10. What is the Range? Range = Biggest - Smallest
The Range is not a form of central tendency, but it is another way to get information from a “set of numbers”.
The range describes the spread of the dataset.
The Range is the difference between the biggest number and the smallest number.
Range = Biggest - Smallest
Temperature Range
Michigan: 35 degrees Florida: 75 degrees
Temperature Range was 40 degrees!

11. Example of Range 4 Range = Biggest – Smallest
Set of Numbers: 2, 3, 1, 1, 0, 1, 2, 4
Subtract: 4 – 0 = 4
Range

12. Remember....
Average
Mean =
Median =
Range =
Middle
Biggest – Smallest

13. You Try! Mandy’s math test scores: 90, 85, 80, 70, 90, 65
90, 85, 80, 70, 90, 65
Determine the following:
Mean _______
Median _______
Range _______

14. Answers! Mandy’s math test scores: 90, 85, 80, 70, 90, 65
90, 85, 80, 70, 90, 65
Mean __80___
Median __82.5_ (find average of 80 & 85)
Range __25___
Order the numbers. Mean : Add numbers: Divide by : Answer: ÷ 6 = So, Mean = 80
Median: There are two numbers in the middle. Average: = 165 ÷ So, Median = 82.5
Mode: occurs the most So, Mode = 90
Range: – 65 = So, Range = 65

15. Closure What did we learn today (key words):
Mean = _________________ ?
Median = _________________ ?
Range = _________________ ?
Which central tendency requires you to first put the numbers in order?
When finding the median, what do you do if there are 2 middle numbers?
Average
Middle
Most
Biggest – Smallest
Median
Average the two middle numbers by adding them together and dividing by 2.