1. Unit 1: Lesson 2 Identify Proportional Relationships Key vocabulary words Proportional relationship – A relationship in which the ratio of the quantities has a constant unit rate (p. 18) Origin the point (0,0) on a coordinate plane where the x- and y-axes intersect (p. 18)

2. Essential Question: How can you decide whether two quantities have proportional relationship? In this lesson you will learn two methods for determining whether two quantities have a proportional relationship. This example shows how to use a table to test for a proportional relationship. Ex 1, The table bellows shows the price and weight of three bunches of bananas. Devon wants to find out if each relationship between the price in dollars and the pounds of bananas is proportional. Two quantities are in a proportional relationship if the ratios fo the quantities have a constant unit rate. This means the unit rate is the same for each ratio PriceUnit Rate Per Pound $0.901.5 $1.051.75 $1.202 Conclusion: The relationship between the two quantities is proportional for each ratio.

3. Ex 2, The table below shows the price and the number if fluid ounces for three containers of orange juice. Sonia wants to find out if the relationship between the price in dollars and the number of fluid ounces is proportional. PriceUnit Rate Per fluid ounce $3.8464 $2.2432 $0.808 Conclusion:

4. The second method used to determine a proportional relationship is to use a graph. Ex 3, Eliza makes these four servings if orange-cranberry juice. If the pairs of quantities in the table are in equivalent proportional relationships, each serving will taste the same. Does the table show proportional relationships that are the same? Orange Juice 23 3 46 5 Graph the ratio pairs. If the points lie in a straight line AND pass through the origin (0,0), then the pairs of quantities are in equivalent proportional relationships.

5. The graph below shows the data from the table. Notice to plot the points the quantities of juices from the table of ratios, you represent all of the ratios A : B as the ordered pair (B, A). Therefore the ratio 2 : 3 is written as the ordered pair (3, 2) Conclusion:

6. Lesson 2 Follow-up Questions: How can you decide if a set of data pairs have a proportional relationship? What are some of the advantages and disadvantages for each method? Unit Rate MethodGraphing Method AdvantagesDisadvantagesAdvantagesDisadvantages