1. Using Proportions Lesson 4-1

2. Ratio: The comparison of two numbers (written in Algebra as a fraction) Proportion: When two ratios are equal to each other Cross Product(s): When we cross multiply/compare diagonally, the special relationship between two ratios in a proportion Math Vocabulary

3. To compare a proportion: 3 = 12 4 16 We use cross products to find if proportions are equal… 3 16 = 4 12 Understanding Proportions

4. Solving Proportions To solve a proportion: 1)Cross multiply 2)Cross multiply 3)Divide to Solve t = 2 9 3

5. Solving Proportions w/ (-) When a negative ratio is present: _ 6 = 4 y 16 *take (-) with either # in only ONE cross product Solve: _ 21 = 7 12 y

6. Practice Justify whether or not the ratios are proportional: a) 3 = 5 4 20 b) 1 = 3 5 15 Solve the proportion: c) w = 6 6 15 d) 10 = _ 5 m 7

7. p. 161 #1-5, 24-27 Homework