1. Proportions

2. What are proportions?
An equation in which two ratios are equal is called a proportion
A proportion can be written using colon notation like this
a : b :: c : d
or as the more recognizable (and useable) equivalence of two fractions.
_ a__ = _ c__
b d

3. Proportions
Means
Extremes
6 x 5 = 3 x 10
30 = 30

4. Proportions
Determine if the following are proportions. 1) 2)

5. Proportions
3 x 60 = 5 x 36
4 x 15 = 8 x 8
180 = 180 60 64
Yes, it is a proportion.
No, it is not a proportion.

6. Solving Proportions 4 = 24 y 30 4(30) = 24y 120 = 24y 24 24 5 = y
5 = y
1. Cross Multiply
2. Solve for the variable.

7. Solving Proportions y 8 8(10) = 5y 80 = 5y 5 5 16 = y 10 = 5
16 = y
1. Cross Multiply
2. Solve for the variable

8. Try one on your own…
3 = 12 y

9. And another…
6 = 12 n