A consumer organization has reported 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 scatter plot, summary statistics, and regression analysis:

Dependent variable is MPG
R-squared = 75.6%
s = 2.413 with 50 - 2 = 48df

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.

Transcribed Image Text:

2 32 28 24 20 2.0 2.5 3.0 3.5 Weight (1000 Ib) Variable Count Mean StdDev 25.0200 4.83394 MPG Wt(1000's) 50 50 2.88780 0.511656 Variable Coefficient SE(Coeff) t-Ratio P-Value Intercept 48.7393 1976 24.7 s0.0001 8.2136 0.674 -12.2 s0.0001 -3 20 25 Predicted (mpg) 30 10 -8-4 Residuals (mpg)