1. Solve Proportional Relationships

2. CROSS PRODUCT RULE In the proportion =, the cross products, a · d and b · c are equal. abab cdcd EX 1) = 2424 1212 44 uses 1. Prove proportionality EX 2) = 5757 3535 2521 2. Disprove proportionality 3. Compare fractions EX 3) 5757 3535 2521 < <

3. Use the cross products to solve proportions with variables. Which help you find missing values. m = 3 Set up proportion. Cross Multiply. Divide by 15 = m5m5 9 15 EX 4) Step 1 Step 2 Step 3 9 x 5= 45 45 ÷ 15

4. Unit rate : a rate whose denominator is 1. It may not always look like a number; watch for words like per or each. miles EX 5) 200/ 4hours How many miles traveled per hour? Step 2: set up proportion = Step 1: highlight rates Miles HoursHour 200 4 X 1 Step 3: Cross multiply and divide 200 X 1 = 200 ÷ 4= 50 X = 50 mph

5. The ratio of students who ordered pizza to those that did not order pizza was 5 : 3. How many students would have pizza if 24 students ordered. EX 6) += not ordered ordered Total ordered = pizza 5 824 X total X = 15

6. Sue needs 9 cups of flour to make 16 batches of cookies. How much flour does she need if she only wants to make a fourth of her recipe. = cups Cups 9 16 X X batches 4 9 X 4 = 36 36 ÷ 16 = 4 16 2 1 4 2 = Cups EX 7)

7. A 12 oz sport drink cost $1.08 and a 16 oz. sport drink cost $1.28. Which drink is the better buy? Step 2: set up proportion = Step 1: highlight rates oz $ $ 16 1.28 X 1 Step 3: Cross multiply and divide EX 8) Since you are comparing you will set up two proportions = oz $ 12 1.08 X 1 $ X = 0.09 X = 0.08 The 16 oz. sport drink is the better buy?

8. Essential Question How do you solve proportions?

9. Date _____________ Solve Proportional Relationships

10. CROSS PRODUCT RULE In the proportion =, the cross products, a · d and b · c are equal. abab cdcd EX 1) uses 1. EX 2) 2. 3. EX 3)

11. You can use the cross product rule to solve proportions with variables. Which help you find missing values. = = 1. 2. 3. = EX 4)

12. How many miles traveled per hour? miles Unit rate : a rate whose denominator is 1. It may not always look like a number; watch for words like per or each. EX 5) / hours Step 2: = Step 1: Step 3:

13. The ratio of students who ordered pizza to those that did not order pizza was :. How many students would have pizza if students ordered. EX 6) += =

14. Sue needs cups of flour to make batches of cookies. How much flour does she need if she only wants to make a fourth of her recipe. = EX 7)

15. A 12 oz sport drink cost $1.08 and a 16 oz. sport drink cost $1.28. Which drink is the better buy? = EX 8) =

16. Essential Question How do you solve proportions?