Educator

Ratios and Proportion

• A ratio is a comparison of two quantities by division.

• A proportion is an equation stating that two ratios are equal.

• Two ratios are equal if and only if their cross products are equal. To solve a proportion, use the fact that the cross products are equal. Set the cross products equal to each other and solve for the unknown value.

• A rate is a ratio of two quantities having different units of measurement.

• Solve problems involving rates by using proportions.

• A scale is a ratio that compares the size of a model to the size of the actual object. Proportions can be used to solve problems involving scales.