Ratios and Proportions

Front

What is a ratio?

Back

A ratio is a comparison of two quantities by division, showing how many times one value contains or is contained within the other.

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal.

Front

How do you solve for an unknown in a proportion?

Back

Cross-multiply the ratios and then solve for the unknown variable.

Front

What does it mean for two quantities to be in direct proportion?

Back

Two quantities are in direct proportion if they increase or decrease at the same rate, meaning their ratio remains constant.

Front

If a recipe calls for 2 cups of sugar for every 3 cups of flour, how much sugar is needed for 9 cups of flour?

Back

6 cups of sugar.

Front

What is the unit rate?

Back

The unit rate is a comparison of two different quantities when they are combined together, expressed as a quantity per one unit of another quantity.

Front

How do you find the unit rate from a ratio?

Back

Divide the first quantity by the second quantity to find the amount per one unit of the second quantity.

Front

What is the scale factor in a scale drawing?

Back

The scale factor is the ratio of a length in the drawing to the corresponding length in the actual object.

Front

If a car travels 120 miles in 2 hours, what is its average speed?

Back

60 miles per hour.

Front

What is the relationship between ratios and fractions?

Back

Ratios can be expressed as fractions, where the first quantity is the numerator and the second quantity is the denominator.