Final answer:
The equation modeling the proportional relationship between time and water used is y = 5x, with y representing the water used in gallons and x representing the time in minutes.
Step-by-step explanation:
The student is asking for an equation that models a proportional relationship between the time in minutes and the water used in gallons. As we look at the given data points, we can determine the constant of proportionality by dividing the gallons of water used by the time in minutes. For example, at time 1 min, 5 gallons are used. Thus, we calculate 5 gallons / 1 min = 5. Doing this for the other data points such as 10 gallons / 2 mins, 15 gallons / 3 mins, and so on, we consistently get the same result. Therefore, the proportional relationship is represented by the equation y = 5x, where y is the gallons of water used and x is the time in minutes. This equation fits all given data points.