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

How do you write a ratio?

Back

Ratios can be written in three ways: as a fraction (a/b), with a colon (a:b), or with the word 'to' (a to b).

Front

What is a proportion?

Back

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

Front

How do you solve a proportion?

Back

To solve a proportion, cross-multiply the terms and set the products equal to each other.

Front

What does it mean for two ratios to form a proportion?

Back

Two ratios form a proportion if their cross products are equal.

Front

If the ratio of male to female teachers is 13:5, what is the ratio of female to male teachers?

Back

The ratio of female to male teachers is 5:13.

Front

In a scale drawing, if the scale is 4 cm:9 ft, what does this mean?

Back

This means that 4 cm on the drawing represents 9 ft in real life.

Front

If a scale drawing of a billboard is 11 cm long, how do you find the actual length using the scale 4 cm:9 ft?

Back

Set up a proportion: 4 cm/9 ft = 11 cm/x ft, then solve for x.

Front

What is the first step in solving a ratio problem?

Back

Identify the quantities being compared and express them as a ratio.

Front

If there are 5 ice cream cones for every 3 brownies, how do you find the number of cones sold if 24 brownies were sold?

Back

Set up a proportion: 5 cones/3 brownies = x cones/24 brownies, then solve for x.