The Temperature Conversions graph represented a continuous relation, so a line was drawn through the points on the graph. Linear equations and graphs can be used to represent discrete relations as well. Suppose a newspaper carrier earns $0.25 for each paper delivered. An equation representing the carrier's daily income is I = 0.25 P, where I represents the income and P represents the number of papers, and a graph of the relation may look like the one shown.



Sketching a graph that contains a large number of discrete data points can take a long time and may look cluttered, so discrete relations are often represented using a continuous graph. The context of the situation is used to decide whether the graph represents continuous or discrete data. So, even though the graph below appears continuous, the number of papers delivered is always a whole number and thus the graph represents a discrete relation.