1. Bell Work: Compare each fraction using <, =, or >
3/ /9
1/ /15
4/9 2/3
8/48 1/8
14/25 14/25

2. Understanding Proportions

3. What is a proportion?
A proportion is an equation stating that two ratios are equal.

4. 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

5. You Try…
Example 1: 9/10, 27/30 If you simplify, 27/30 = 9/10, so YES, THESE RATIOS ARE PROPORTIONAL!

6. You Try…
Example 2: 72/81, 7/9 8/9 = 7/9 NO!

7. You Try…
Example 3: 2/5, 8/20 2/5 = 2/5 YES!

8. To complete a proportion…
Write a rate for what you “KNOW”
Equals sign
Follow same order & set up second rate using a variable for what you “DON’T KNOW”

9. Example
÷ 5 35 7 = 40 8
÷ 5

10. Example 4:
A hybrid car can travel 260 miles using 5 gallons of gas. How many miles can it go using 15 gallons of gas?
Step 1
Step 2
Step 3 =
x mi
X = 260 x 3
X = 780
260 mi
15 gal
5 gal