We will learn to represent the relationship between two quantities in a ratio.

• A ratio is a comparison between two quantities that have the same unit of measurement.
• The ratio a to b is written as a:b or in the form of an \({a \over b}\) fraction.
• Ratios are written in the form of whole numbers without any unit of measurement.

There are 3 types of ratios:

1. The ratio of parts to other parts.
2. The ratio of parts to a whole.
3. Overall ratio to parts.

For example:

There are 12 marbles in the container, namely 5 green marbles and 7 blue marbles.

• The ratio of the number of green marbles to blue marbles is 5:7.
• The ratio of the number of blue marbles to green marbles is 7:5.
• The ratio of the number of blue marbles to all marbles is 7:12.
• The ratio of the number of all marbles to green marbles is 12:5.