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Mode

Mean

Range

Median

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, Whats my average?

What we should say is, Whats my mean?

Mean

This is what we usually mean when we say Whats

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

Your median test grade is 92 half the time you

score below 92 and half the time above 92

The middle number is the median

Your grades on six tests 95, 85, 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 Or 92 94

186 186 divided by 2 93

The middle is between 2 numbers

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 dont have to have a mode. Some data sets

have no mode or no number that occurs more than

others Some might have two modes

RANGE

Asks the Question How spread out is my data?

Another way to describe 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

Its Time To Practice!

Number of pets owned by 7 students

2, 1, 1, 4, 3, 2, 1

2

What is the mean

What is the median

2

1

What is the Mode

3

What is the Range

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..