1. PROPORTIONS

2. PROPORTIONS
An equation stating that two ratios are equal.

3. First way to determine if a ratio is proportional…
Write both ratios in simplest form and see if they are equal.

4. Determine whether the ratios in each pair can form a proportion by writing each ratio in simplest form.

5. For each class, look at the ratio of the number of students who saw a movie to the total number of students. Can the ratios form a proportion? Did You See a Movie This Weekend?
Class
Yes
Total Number A 10 24 B 25 60

6. Second way to determine if a ratio is proportional…
Show that a common multiplier connects their numerators and denominators.

7. Determine whether the ratios in each pair can form a proportion by finding a common multiplier.

8. Third way to determine if a ratio is proportional…
Cross Products Property Found by multiplying the numerator of one ratio by the denominator of the other ratio.

9. Determine whether the ratios in each pair can form a proportion by using cross products.

10. Use any method to solve.
A certain shade of green paint requires 4 parts blue to 5 parts yellow. If you mix 16 quarts of blue paint with 25 quarts of yellow paint, will you get the desired shade of green? Explain.

11. SOLVING PROPORTIONS

12. Oranges are 6 for $2.34. Find the cost of 8 oranges.
FIRST METHOD…(using unit rates)
Step 1: Find the unit price.
Step 2: Multiply the unit price by the number of oranges.

13. Postcards cost $2.45 for 5 cards. How much will 13 cards cost?

14. Swimming goggles cost $84. 36 for a case of 12
Swimming goggles cost $84.36 for a case of 12. At this rate, how much will it cost to get new goggles for 17 members of a swim team?

15. Oranges are 6 for $2.34. Find the cost of 8 oranges.
SECOND METHOD…(using cross products)
Step 1: Set-up a proportion.
Step 2: Find the cross product
Step 3: Solve

16. Solve using cross products.

17. Solve using cross products.

18. Solve using mental math.

19. Solve using mental math.