An engineer is interested in the relationship between the weight of a car (measured in pounds) and the fuel economy (measured in miles per gallon of gas). To investigate the relationship, she collects a simple random sample of 10 cars and records their weight and fuel efficiency. She finds the equation of the least-squares regression line to be ŷ = 69 – 0.0114x, where ŷ is the fuel efficiency (mpg) and x is the weight (in pounds). The residual plot is shown.