Concept

A ratio is a comparison of two quantities by division. Ratios describe a part-to-part comparison or a part-to-whole comparison. 

Two ratios that have the same value are called equivalent ratios. 

Rule

The order of the values in a ratio relates directly to the order of the quantities described.

Ratios are written three ways: as a fraction, with a colon, and with the word “to.”

To find an equivalent ratio, multiply or divide both quantities by the same number. It is the same process as finding equivalent fractions.

Example

Select the ratio of stars to circles.

Solution

1. The order of the values in a ratio relates directly to the order of the quantities described: red bears to blue bears. The number on the left will represent the number of red bears. The number on the right will represent the number of blue bears. 4:12

2. To find an equivalent ratio, multiply or divide both quantities by the same number. Working with 4:12, find the equivalent ratio from the choices given.

To get a 1 on the left side divide:

1:3 is an equivalent ratio to 4:12

As shown in the picture, for every 1 red bear there are 3 blue bears.

Pre-requisite Skills

Understand Ratios (6.6.1)

Equivalent Fractions (4.14.5)