1. Ratios and Proportions Unit 4, Lesson 7 peer.tamu.edu/NSF_Files/Ratios%20and%20Proportions.ppt‎

2. Ratios: http://www.brainpop.com/math/ratioproport ionandpercent/ratios/preview.wemlhttp://www.brainpop.com/math/ratioproport ionandpercent/ratios/preview.weml

3. What is a Ratio? A ratio is a comparison of two numbers. Ratios can be written in three different ways: a to b a:b Ratios are expressed in simplest form

4. How to Use Ratios? The ratio of boys and girls in the class is 12 to11. 4cm 1cm The ratio of length and width of this rectangle is 4 to 1.. The ratio of cats and dogs at my home is 2 to 1

5. How to simplify ratios? Now I tell you I have 12 cats and 6 dogs. Can you simplify the ratio of cats and dogs to 2 to 1? =

6. More examples… = = = = =

7. Proportions: http://www.brainpop.com/math/ratioproport ionandpercent/proportions/http://www.brainpop.com/math/ratioproport ionandpercent/proportions/

8. Now, on to proportions! What is a proportion? A proportion is an equation that equates two ratios

9. Properties of a proportion? 2x6=12 3x4 = 12 Cross Product Property

10. How about an example? Solve for x: 7(6) = 2x 42 = 2x 21 = x

11. How about another example? Solve for x: 7x = 2(12) 7x = 24 x =

12. Define: Let t = time needed to ride 295 km. In 2000, Lance Armstrong completed the 3630-km Tour de France course in 92.5 hours. Traveling at his average speed, how long would it take Lance Armstrong to ride 295 km? 3630t = 92.5(295) 3630 t ≈ 7.5 3630 92.5 295 t kilometers hours Write: = Applications of Proportions 3630