2. Proportions  A proportion is an equation with a ratio on each side. It is a statement that two ratios are equal.  3 = 6 is an example of a proportion. 4 8 (A ratio is a fraction.)

3. How can you tell if ratios are in proportion?

4. Tell whether the ratios are proportional. 4 10 6 15 Since the cross products are equal, the ratios are proportional. 60 = ? 60 = 60 Find cross products. 60 4 10 6 15

5. Tell whether the ratios are proportional. Since the cross products are equal, the ratios are proportional. 20 20 = 20 Find cross products. 20 2424 5 10 2424 5 10 = ?

6. Solving Proportions  When you do not know one of the four numbers in a proportion, set the cross products equal to each other and solve.

7. Solve the Proportion 6p = 12 5 p = 10 6p = 60 Find the cross products. Solve. 5656 p 12 = ; the proportion checks. 5656 10 12 =

8. Solve the Proportion 14 3 = 2g 21 = g 42 = 2g Find the cross products. Solve. 2323 14 g = ; the proportion checks. 2323 14 21 =