Assessing Model Fit with Residuals Practice Test

A researcher fits a line $$y = 0.6x + 5$$ to model a plant’s height, where $x$ is the number of days since planting (days) and $y$ is the plant’s height (centimeters). What does the y-intercept represent in this context? Include units in your interpretation.

A car rental company models the total cost of renting a car with $$y = 50 + 30x,$$ where $x$ is the number of days the car is rented (days) and $y$ is the total cost (dollars). Which interpretation of the slope is correct? Include units in your interpretation.