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Transcript 
7th Grade Math
Mean, Median, and Range
Obj. 5b
Central Tendency
When you have a “set of data” (or numbers), there are 2 different
ways you can find the center of the data.
1)
2)
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
Mean = Average
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.
Step 1
Step 2
Add the numbers.
Divide by the # of
items in the dataset.
Mean = Average
Step 1
Step 2
Add the numbers.
Divide by the # of
items in the dataset.
Set of Numbers:
2, 3, 1, 1, 0, 1, 2, 4
Add the numbers: 2 + 3 + 1 + 1 + 0 + 1 + 2 + 4 =
Divide by total items: 14 ÷ 8 =
1.75
Mean
14
Median = Middle
What is the Median?
The Median is the middle number.
 How do you find the Median?

If there is just 1
middle #:
your done!
ORDER
FIND
the numbers.
the middle #.
If there are 2
middle #’s
Median = Middle
Average the 2
middle numbers.
Example of Median
If there is just 1
middle #:
your done!
ORDER
FIND
the numbers.
the middle #.
If there are 2
middle #’s
Average the 2
middle numbers.
Add the
2 middle
numbers
Set of Numbers:
2, 3, 1, 1, 0, 1, 2, 4
Arrange in order:
0, 1, 1, 1, 2, 2, 3, 4
1 + 2 = 3
3 ÷ 2 = 1.5
Median
Then,
Divide
by 2
Range = Biggest – Smallest
What is the Range?

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
Example of Range
Range = Biggest – Smallest
Set of Numbers:
2, 3, 1, 1, 0, 1, 2, 4
Subtract:
4–0=
4
Range
Remember....
Mean
Average
=
Median
= Middle
Range
= Biggest – Smallest
You Try!
Mandy’s math test scores:
90, 85, 80, 70, 90, 65
Determine the following:
Mean
Median
Range
_______
_______
_______
Answers!
Mandy’s math test scores:
90, 85, 80, 70, 90, 65
65 70 80 85 90 90
Mean
Median
Range
__80___
__82.5_
__25___
(find average of 80 & 85)
Closure

What did we learn today (key words):
Mean =
Median =
Range =

Average
_________________ ?
Middle_________________ ?
Most
_________________ ?
Biggest – Smallest
Which central tendency requires you to first put
the numbers in order?
Median

When finding the median, what do you do if there
are 2 middle numbers?
Average the two middle numbers by adding them together and dividing by 2.
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