Final answer:
A relationship where the constant of proportionality is 1/3 means that one quantity is one-third of another quantity in a consistent manner, and can be mathematically represented by an equation such as y = (1/3)x.
Step-by-step explanation:
The question is asking about the constant of proportionality, which is the factor that relates two quantities that are proportional to each other. In mathematics, especially in ratios and proportions, we often encounter situations where one variable is a constant multiple of another. For example, in the given information where p (pay) is being paid at a rate per n (number of calls), the constant of proportionality would be the rate per call ($2.50). If the constant of proportionality is 1/3, it means for every 1 unit of one quantity, there are 1/3 units of the second quantity consistently. This can be written in the form of y = (1/3)x, where y varies directly with x.