Final answer:
The equation y = 12x represents a proportional relationship with a constant of proportionality of 12, indicating that the total cost increases at a constant rate per student with no fixed cost.
Step-by-step explanation:
The function described by the equation y = 12x for the chess team's admission cost to a waterpark is a proportional relationship, since the ratio of total cost to the number of students remains constant. This means for every additional student, the total cost increases at a constant rate of 12. There is no starting fee or fixed cost. A proportional function can be identified by its having a graph that is a straight line passing through the origin (0,0) and it can be represented mathematically in the form of y = mx where m is the constant of proportionality. In this case, the slope or the constant of proportionality is 12, which represents the cost per student for admission.