1. Understanding Proportions
Lesson 6-3

2. Vocabulary
A proportion is an equation stating that two ratios are equal.
To prove that two ratios form a proportion, you must prove that they are equivalent. To do this, you must demonstrate that the relationship between numerators is the same as the relationship between denominators.

3. Examples: Do the ratios form a proportion?
Yes, these two ratios DO form a proportion, because the same relationship exists in both the numerators and denominators. 7 21 , 10 30
x 3
÷ 4 8 2
No, these ratios do NOT form a proportion, because the ratios are not equal. , 9 3
÷ 3

4. Completing a Proportion
Determine the relationship between two numerators or two denominators (depending on what you have).
Execute that same operation to find the part you are missing.

5. Example
÷ 5 35 7 = 40 8
÷ 5

6. Homework Time