Measure of Central Tendency Grade 8.pptx

GOOD
AFTERNOO
N GRADE 8
TEACHER JON
MATH 8

Mean
Median
Mode
Range
4 Ways to Measure
Data

Objectives
1. Understand what mean,
median, mode, and range are
2.Learn how to calculate each
measure
3.Apply these concepts to solve
real world problems
In this presentation we will:

Mean, median, mode, and range
are measures used to analyze
number sets. These number sets
are a collection of numbers. A
number set is defined by the total
numbers inside the set. We can use
paraentheses to define the set. A
set can look like this:
A Number Set
{12, 15, 18, 20, and 25}

Mean is the average of the number
set.
Mean
To calculate mean, we add
together all the numbers in a set,
and then divide by the total count
of numbers in the set.
Mean = (sum of all numbers) ÷ (total
count of numbers)

Let’s use this number set as an
example.
Mean - Example
Mean = (sum of all numbers) ÷ (total
count of numbers)
{10, 15, 20, 25, and 30}
Mean = (10 + 15 + 20 + 25 + 30) ÷ (5)
Mean = 20

Median is the middle number in a
set where the numbers are
arranged from smallest to largest.
Median
If the number set is odd, the
middle number is the median.
If the number set is even, the
middle number is the average of
the two middle numbers.

Let’s use this number set:
Median - Example
#1
{12, 25, 18, 20, and 15}
First arrange numbers from
smallest to largest.
{12, 15, 18, 20, and 25}
This number set is odd because
there are 5 numbers in the set. The
medium is 18.

Let’s use this number set:
Median - Example
#2
{12, 25, 18, 20}
First arrange numbers from smallest to
largest.
{12, 18, 20, and 25}
This number set is even because there
are 4 numbers in the set. We take the
average of the two middle numbers.
Median = (18 + 20) ÷ 2 = 19

Mode is the number that appears
most often in a number set.
Mode
A number set can have:
• one mode
• a number of modes
• no modes at all

Let’s take a look at this number set.
Mode - Example
{7, 8, 9, 9, 10, 10, 12}
This set has two numbers that
appear more than once. Therefore
the modes for this set are 9 and 10.

Range is the difference between
the largest and smallest values in a
number set.
Range
Range = (largest value) - (smallest
value)

Let’s look at this number set:
Range - Example
Range = (largest value) - (smallest
value)
{5, 10, 15, 20, and 25}
Range = 25 - 5
Range = 20

Mean
Median
Mode
Range
Let’s Practice!
Find each of the following:
{5, 10, 12, 15, 12, 20, and 25}

Mean 13.85
Median 12
Mode 12
Range 20
Let’s Practice!
(Answers)
Find each of the following:
{5, 10, 12, 15, 12, 20, and 25}

Let’s look at real world examples of
when to use mean, median, mode
and range.
Real World Examples
• Average test scores in a class
• Middle income salary in a city
• Most common shoe sizes in a
store
• Temperature ranges in a month

To summarize what we learned
today, take notes on key words.
Summary
• MEAN is the AVERAGE number
• MEDIAN is the MIDDLE number
• MODE is the COMMON number
• RANGE is the DIFFERENCE
between the largest and
smallest number

Measure of Central Tendency Grade 8.pptx

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