1. Chapter 3-9 Proportions –pgs 148-151 9M5:Solve problems involving rates

2. Proportion 2 ratios (fractions) that are equal. Ex:

3. Cross Products Product of opposite numerators and denominators are equal (for equal fractions) 36 We use this property to solve a proportion! =

4. Notes Use cross products to solve Used for many types of problems (unit rate, scale drawings ratios…..) any time two units are being compared Set up word problems in words first!!!!

5. Example #1 Solve for x. 60 = 3x 33 20 = x

6. Example #2 A certain car can travel 180 miles on 12 gallons of gas. How far can this car travel on 20 gallons of gasoline? Set up in words Now solve!

7. Example 3 A blue print is drawn so that ¼ in is 1 foot of the original size. If the actual kitchen is 14 feet long, how long will it appear on the print? Set up in words i = The kitchen on print is 3 ½ inches

8. Example 4 Twenty deer are tagged and released into the wild. On a hunt in that area 3 of the 25 deer killed are tagged. What is the approximate population of deer in that area? Set up in words 3 3 500 = 3x 167 ≈ x About 170 deer in area

9. Example 5 The ratio of boys to girls in a class is 3:2. If there are 210 students, how many are girls? This one is tricky! What is being compared? 3 boys and 2 girls is 5 students Now Solve!!

10. Assignment 3-9/150-151/22-34e,35-43,45,46,55-59,61 (Omit 39)