Ratios and Proportions I

Front

What is a ratio?

Back

A ratio is a comparison of two quantities that shows 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: using a colon (e.g., 2:3), as a fraction (e.g., 2/3), or with the word 'to' (e.g., 2 to 3).

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, you can use cross-multiplication. If a/b = c/d, then a*d = b*c.

Front

What is an equivalent ratio?

Back

Equivalent ratios are two or more ratios that express the same relationship between numbers.

Front

If the ratio of dogs to cats is 2:3, how many cats are there if there are 10 dogs?

Back

There are 15 cats. (2/3 = 10/x; cross-multiply: 2x = 30; x = 15)

Front

What is the ratio of triangles to squares if there are 4 triangles and 3 squares?

Back

The ratio is 4:3.

Front

In a recipe, the ratio of sugar to flour is 1:4. If you use 2 cups of sugar, how much flour do you need?

Back

You need 8 cups of flour. (1/4 = 2/x; cross-multiply: 1x = 8; x = 8)

Front

What is the ratio of 5 apples to 10 oranges?

Back

The ratio is 1:2.

Front

If there are 30 students and the ratio of boys to girls is 2:3, how many girls are there?

Back

There are 18 girls. (2/5 = x/30; cross-multiply: 2*30 = 5x; x = 12; girls = 30 - 12 = 18)