A comparison of two quantities that have different units of measure.
For example, the amount of flour and sugar in a recipe for cookies are a proportional relationship. Suzanne wants to bake four batches of cookies. Her recipe says that 1 cup of flour and 2 cups of sugar are needed to make 1 batch of cookies. In order to quadruple the recipe, Suzanne must multiply the quantity of every ingredient by four. imgsrc="images/examples/prop-relate1.gif" width="98" height="63"> After multiplying the original quantities by four, Suzanne is left with the proportion
The ratios of flour to sugar for the cookie receipe are in a proportional relationship with one another since they form equal ratios.