1. 5. 2 Proportions 5. 2 Extension: Graphing Proportional Relationships 5
5.2 Proportions 5.2 Extension: Graphing Proportional Relationships 5.3 Writing Proportions
9/26/16

2. Proportions
A proportion is an equation stating that two ratios are equivalent.
Two quantities that form a proportion are called proportional.
You can check if quantities are proportional either by simplifying the fractions or by using the cross products property
Cross products property: the cross products of a proportion are equal.

3. Example 1
Are and proportional? Prove your answer in two ways.

4. Example 2
Are x and y proportional? x 2 3 4 y 6 7 8

5. Graphs of Proportional Relationships
Go through the origin (0,0)
Have a constant rate of change (slope)
Therefore, all graphs of proportions are straight lines passing through the origin

6. Page 175 Example 1

7. Example 3
Interpret each point on this graph of a proportional relationship.

8. Writing Proportions Example 4
Your units must match either horizontally or vertically, not diagonally.
Example 4
You are making cookies. 2 cups of chocolate chips makes 3 dozen cookies. How many cups of chocolate chips do you need to make 12 dozen cookies?

9. Example 5
Your test is out of 30 points. How many do you need to get correct to score at least 80%? Solve the problem using a proportion.