Difficult# Interpreting a Residual Plot: Speed and Average Gas Mileage

APSTAT-XH1CHU

A least squares regression analysis of average gas mileage versus speed (mph) produces the following residual plot:

Based on the residual plot, which of the following statement(s) must be TRUE?

I.The relationship between speed and average gas mileage is non-linear.

II.The average gas mileage decreased as speed increased from $35$ mph to $60$ mph.

III.The regression equation would overestimate the average miles per gallon the car gets when the speed is $10$ miles per hour.