Ratios
Regular Textbook Page 402-406
Objective
• I can use ratio language to describe the
relationship between two quantities.
Ratios
• What is a ratio?
• A ratio is a comparison of two quantities.
(Uses division to compare two number)
• It shows how many times as great one
quantity is to another.
• The numbers in the ratio are called terms.
There are several ways to write ratios!
Team
Wins
Loses
Firelands
8
3
Keystone
7
2
Oberlin
6
4
• There are three ways to write ratios:
• Words
Numbers
• Wins to losses
8 to 3
• Wins
8
• losses
3
• Wins:losses
8:3
All three ways are read “ the ratio of blank to blank. So 8:3 is read,
“the ratio of eight to three.
Teams
Wins
Losses
Firelands
8
3
Keystone
7
2
Oberlin
6
4
• Write a ratio:
• A. Keystones wins to losses
• 7:2 or 7 to 2 or 7/2
• Write a ratio of wins to games played for Oberlin.
• 6 to 10 or 6:10 or 6/10
Write me a ratio!
• Teacher to students in this room.
• Students to teachers.
• Boys to girls
• Boys to all students.
Ty’s Video Collection
Comedies=8, Dramas= 3 Cartoons= 2 Sci Fi=1
• Describe the relationship between the drama
videos and the Sci Fi videos.
• 3 to 1
• Analyze relationships:
• The ratio of floor seats to balcony seats in a
theater are 20:1. Does the theater have more
floor seats or more balcony seats. How do
you know?
Equivalent Ratios are?
• Equivalent Ratios: ratios that name the same
comparison or that have the same value.
Equivalent Ratios
• You can find equivalent ratios by using table or
multiplying or dividing both terms of the ratio
by the same number.
Multiply both terms by the same number.
• Ratio: 3 cats to 5 dogs
• You can write an equivalent ratio by
multiplying both terms by the same number.
• So multiply both terms by 2.
• An equivalent ratio would be
• 6 to 10
• 5
• 7
n
35
• N=
• What did you do to 7 to get to 35. You must
do the same to 5.
Some more equivalent Ratios
• Write me an equivalent ratio:
• 6:21
• 3
9
You try!
• Write a ratio to triangle
to rectangles in three
ways.
• Write me three
equivalent ratio for
triangles to rectangles
• Multi step
The ratio of North American Butterflies to south
American butterflies at a butterfly park is 5:3.
The ratio of South American butterflies to
European butterflies is 3:2. There are 30 North
American Butterflies at the park.
How many South American butterflies are
there?
How many European Butterflies are there?
Homework
Workbook Pages 101-102
Odds