Transcript Mean, Median, Mode, and Range Review

WHAT DO THEY ALL MEAN?
A number that helps
describe a set of data is
an AVERAGE!
Sometimes called a
MEASURE OF
CENTRAL TENDANCY
ALL OF THESE ARE
AVERAGES:
•MEAN
•MEDIAN
•MODE
We use the word the
wrong way when we ask
a teacher, “What’s my
average?”
What we should say is, “What’s my mean?”
Mean
This is what we usually
mean when we say
“What’s my average.”
We could say, “What grade do I
normally get?”
How is the mean of a set of
numbers found?
• Add all the numbers in the set
together.
• Divide the sum by the number of
data items in the set.
• The quotient is the mean of the
set of numbers.
• Example: 10, 18, 12 and 16
– Add 10 + 18 + 12 + 16 = 56
– Divide 56 by 4
– The mean is 14
Median
• Is the number that is in the middle
of a set of numbers.
• Half the numbers are below the
median and Half the numbers are
above the median
How is the median of a set of
numbers found?
• Arrange the numbers in the set in order
from least to greatest.
• The middle number is the median of a set
of numbers.
• If more than one number is in the middle
of the set of numbers, the mean of those
two numbers is the median of the set of
numbers.
Your grades on five tests:
95, 87, 92, 100, and 85
Put them in order from least to greatest
85, 87, 92, 95, 100
The middle number
is the median
Your median test grade is
92 – half the time you
score below 92 and half
the time below 92
Your grades on six tests:
95, 87, 92, 100, and 94
Put them in order from least to greatest

85, 87, 92,
94, 95, 100
The median is the mean of 92 and 94
The middle is
between 2
numbers
Or
92 + 94 = 186
186 divided by 2 = 93
Mode
The number in a data set that occurs most often
Your grades: 95, 87, 85, 100, 100
Your mode is 100
Most of the time you get a 100
How do I identify the mode of a set
of numbers?
• Arrange the set of numbers in order from
least to greatest.
• The number that occurs the most often is
the mode of that set of numbers.
You don’t have to have a
mode…….
Some data sets have no
mode or no number that
occurs more than others
Some might have two
modes
Another
way to
describe
data
Asks the
Question:
How spread out
is my data?
How is the range of a set of
numbers identified?
• Arrange the numbers in the set in order
from least to greatest.
• Subtract the lowest number from the
highest number in the set of numbers.
• The difference of the two numbers is the
range of a set of numbers.
Back to your test Scores:
95, 87, 92, 100, and 94
Your highest score is a 100
Your lowest score is 87
Your range is 100 – 87 = 13
The range = 13
It’s Time To Practice!
Number of pets owned by 7 students:
2, 1, 1, 4, 3, 2, 1
What is the mean
2
What is the median
2
What is the Mode
1
What is the Range
3
4 ways to describe data
The Mean – what we usually think of as
the average…..
The Median – The middle number in a
data set…..50% of the numbers are above and
50% are below the median
The Mode – The number that occurs
most often…..
The Range – the difference between the
smallest and bigest number…..