Explain how part-to-part ratios are different from, but related to, part-to-whole ratios.

Ratios can be divided into part-to-part ratios and part-to-whole ratios. Part-to-part ratios provide the relationship between two distinct groups. Part-to-whole ratios provide the relationship between a particular group and the whole populations (including the particular group). For example, 3/5 of the students in the class are girls, or the mixture is 40% rye grass (40% is equivalent to saying 40 of every 100 parts).