A ratio of 1:20 means that for every 1 part of one quantity, there are 20 parts of another quantity. This can be used in various contexts, such as mixing ingredients, comparing sizes, or analyzing data. For example, if you have 1 cup of sugar and want to mix it with water in a 1:20 ratio, you would use 20 cups of water. Ratios help simplify comparisons and make it easier to understand relationships between different quantities. In a classroom setting, if there is a ratio of 1:20 of teachers to students, it indicates that for every teacher, there are 20 students present.