1. Lesson 3.6- Ratios and Proportions, pg. 155 Objectives: To determine whether two ratios form a proportion. To solve proportions.

2. Vocabulary Ratio: a comparison of two numbers by division. Examples: x to y x : y x/y Proportions: an equation stating that two ratios are equal. Example:

3. Extremes: in the ratios, a and d are the extremes. Means: in the ratios,c and b are the means. Rate: the ratio of two measurements having different units of measure. Scales: a ratio or rate used when making a model of something that is too large or too small to be conveniently shown at actual size.

4. Ex. 1: Determine whether ratios form a proportion. 1.

5. Another way to determine whether two ratios form a proportion is to use cross products. If the cross products are equal, then the ratios form a proportion.

6. Ex. 2: Use cross products. 1.2.

7. Solve Proportions You can write proportions that involve a variable. To solve proportions, use cross products and the techniques used to solve other equations. Ex.

8. Ex. 3: Solve a proportion. 2. 1.

9. 3.4.

10. Ex. 4: 1. The Lehmans’ minivan requires 5 gallons of gasoline to travel 120 miles. How much gasoline will they need for a 350-mile trip?

11. 2. Seth earns $152 in 4 days. At that rate, how many days will it take him to earn $532?

12. NBA #20, page 158, problems 12-34 even