3. A proportion is a statement of equality of two or more ratios Remember: A ratio is a comparison of two numbers by division

4.  Cartoons  Food and Nutrition  Fashion Design  Maps  Artists  Metric System

5.  http://www.brainpop.com/math/ratiopropor tionandpercent/proportions/

6. Find the two things you are comparing!! First Step:

7. Suppose it takes 48 chicken fingers to feed Mr. Young’s 4th grade class of 20 students. How many chicken fingers would be needed for 30 students?

8. And the answer is……. Chicken Fingers and Students Chicken Fingers Students ---------------------- OR ------------- Students Chicken Fingers As a Ratio this looks like…..

9. Jane ran 100 meters in 15 seconds. How long did she take to run 1 meter?

10. And the Answer is…. Meters and Seconds MetersSeconds ---------- OR------------ SecondsMeters As a Ratio this looks like…..

11. A car travels 125 miles in 3 hours. How far would it travel in 5 hours?

12. And the answer is…. Miles and Hours As a Ratio this looks like….. MilesHours ---------OR-------- Hours Miles

13. Make the two ratios (fractions) that you know Second Step:

14. Suppose it takes 48 chicken fingers to feed Mr. Young’s 4th grade class of 20 students. How many chicken fingers would be needed for 30 students? First Step: Chicken FingersStudents ---------------------- OR -------------- StudentsChicken Fingers

15. Suppose it takes 48 chicken fingers to feed Mr. Young’s 4th grade class of 20 students. How many chicken fingers would be needed for 30 students? And the answer is…. Chicken Fingers48 X -------------------- ------AND ----- Students20 30

16. FYI Can you flip the ratio so that students were on top and chicken fingers were on bottom? YES! If you flip the ratios so that students are on top and chicken fingers were on bottom you must just be careful to do this for all your ratios. Therefore then 48/20 would change to 20/48 and x/30 would become 30/x.

17. Chicken Fingers 48 X -------------------- ---- AND ---- Students 20 30 OR Students 20 30 ----------- ------ AND ------- Chicken Fingers 48 X

18. Jane ran 100 meters in 15 seconds. How long did she take to run 1 meter? MetersSeconds ---------- OR------------ SecondsMeters First Step:

19. Jane ran 100 meters in 15 seconds. How long did she take to run 1 meter? And the answer is….. Meters 100 1 --------- ------ AND ------- Seconds 15 X

20. A car travels 125 miles in 3 hours. How far would it travel in 5 hours?

21. And the answer is….. Miles 125 X ------- ------ AND ------- Hours 3 5

22. Third Step: Set the two ratios EQUAL to each other

23. 1. Chicken Fingers ---------------------- Students 2. 48 X ---- AND ---- 20 30 3. 48 X ----- = --- 20 30 Suppose it takes 48 chicken fingers to feed Mr. Young’s 4th grade class of 20 students. How many chicken fingers would be needed for 30 students?

24. Jane ran 100 meters in 15 seconds. How long did she take to run 1 meter?

25. And the answer is…… 1.Meters ---------- Seconds 2. Meters 100 1 --------- ------ AND ------- Seconds 15 X 3. 100 1 ------ = ------- 15 X

26. A car travels 125 miles in 3 hours. How far would it travel in 5 hours?

27. And the answer is….. 1. Miles ------- Hours 2. Miles 125 X ------- ------ AND ------- Hours 3 52 3. 125 X ------ = ------- 3 5

28. Fourth Step: Cross Multiply

29. Cross Multiply means that you MULTIPLY DIAGONALLY across….. …….Like crisscross apple sauce when you are sitting And then….. Set the two products (ANSWERS) EQUAL to each other 4X = 63

30. Fifth Step: Solve for X!!!

31. 48 X ----- = --- 20 30

32. And the answer is…. 30 students would eat 72 chicken fingers

33. 100 1 ------ = ------- 15 X

34. And the answer is… (100)(X)= (15)(1) 100X= 15 X= 15/100 X=.15 It took Jane.15 seconds to run a meter 100 1 ------ = ------- 15 X

35. 125 X ------ = ------- 3 5

36. (125)(5) = (3)(X) 625 = 3X 625/3=X X= 208.3 In 5 hours the car would have traveled 208.3 miles. 125 X ------ = ------- 3 5

37. Mix 3 liters of water with 4 lemons to make lemonade. How many liters of water are mixed with 8 lemons.

38. 1. What are you comparing? Liters and Lemons LitersLemons -------OR ------- LemonsLiters Mix 3 liters of water with 4 lemons to make lemonade. How many liters of water are mixed with 8 lemons.

39. 2. What are your two ratios? Liters 3 X --------- ------ AND ------ Lemons 4 8 3. Set the two ratios equal to each other 3 X ---- = ----- 4 8 Mix 3 liters of water with 4 lemons to make lemonade. How many liters of water are mixed with 8 lemons.

40. 4. Cross Multiply 3 X ---- = ----- (4)(X) = (3)(8) 4 8 5. Solve 4X= 24 X= 24/4 X= 6 You will need 6 liters of water for 8 lemons.

41. 3 gallons of paint cover 900 square feet. How many gallons will cover 300 square feet?

42. The answer is 1 gallon of paint for 300 square feet.