“Don’t be so MEAN!”

Words spoken by an AVERAGE

man.

Average

• A number that typifies a set of numbers of which it is a function.

Huh?

Mean

• The average value of a set of numbers.

Huh?

Average=Mean

• The average is the mean.

• The mean is the average.Huh?

Let’s try it this way.• The average (or mean) of data is computed by

– 1. Adding all the data together (sum).– 2. Dividing that sum by the number of data.

Rocks Collected

Andrew 5 rocks 5

Shequeta 10 rocks 10

Karen 2 rocks 2

Byron 7 rocks + 7

5 + 10 + 2 + 7 = 24

24 ÷ 4 = 6So the average number of rocks collected was 6.

Here’s another example.The Aqua Club

Feona 3 fish 3

Lynda 2 fish 2

Chris 10 fish 10

Peter 6 fish 6

Cherelle 4 fish + 4

3 + 2 + 10 + 6 + 4 =25

25 ÷ 5 = 5

So the average number of fish owned by members of the Aqua club was 5.

You can find the average of your test grades.

Sam’s Spelling Grades

Jan. 9 90 % 90

Jan. 16 85 % 85

Jan. 25 82 % 82

Feb. 1 100 % 100

Feb. 8 100 % 100

Feb. 15 88 % + 86

90 + 85 + 82 + 100 + 100 + 86 = 543

543 ÷ 6 = 90.5So the average of Sam’s spelling grades is 90.5 which is rounded up to 91 which is an A.

Find the average of this data.Amount of rainfall

Week 1 4 inches

Week 2 2 inches

Week 3 6 inches

The average rainfall during these three weeks was 4 inches.

Find the average of this data.The Hip Hop Club’s CD Collections

Nathaniel 15

Belinda 21

Kareem 14

Angelo 17

Jessie 33

The average number of CDs owned by the members of the Hip Hop Club’s members is 20.

Find the average of this data.Books in the classroom library

Realistic fiction 18

Science fiction 17

Fairy Tales 5

Historical Fiction 12

Biographies 20

Poetry 30

How to books 5

Other nonfiction 13

There is an average of 15 of each genre in the classroom library.

Find the average of this data.Mr. Postman’s tie collection

Sports ties 10

Animal ties 7

Music ties 12

School ties 9

Mr. Postman has an average of 9.5 of each kind of tie.

Last one!Cities with over 100,000 people

Ohio 8

Texas 11

Pennsylvania 12

New York 13

Illinois 7

Michigan 9

Florida 10

California 16

Kansas 4

Virginia 6These states have an average of 9.6 cities with a

population of over 100,000.