Fuel economy A consumer organization has reported T test data for 50 car models. We will examine the association between the weight of the car (in thousands of pounds) and the fuel efficiency (in miles per gallon).

Here are the scatterplot, summary statistics, and regression analysis:

a) Is there strong evidence of an association between the weight of a car and its gas mileage? Write an appropriate hypothesis.

b) Are the assumptions for regression satisfied?

c) Test your hypothesis and state your conclusion.

Fuel efficiency (mpg) 32 28 24 20 2222 2.0 2.5 3.0 3.5 Weight (1000 lb) Variable Count Mean StdDev MPG 50 25.0200 4.83394 Wt(1000's) 50 2.88780 0.511656 Dependent variable is MPG R-squared = 75.6% s = 2.413 with 50 - 2 = 48 df Variable Coefficient SE(Coeff) t-Ratio P-Value Intercept 48.7393 1.976 24.7