Automobiles. An editor for a major automobile magazine has collected data on the best-selling cars in the United States. He is interested to know about the relationship between highway mileage and weight of the vehicles.

Here are the regression and residual output, where the response variable is Mileage.

Dependent variable is: Mileage R-squared = 54.6%

s = 2.86 with 30 - 2 = 28 degrees of freedom Variable Coefficients Error t-stat P-value Intercept 46.3298 3.7390 12.3909 6.97E-13 Weight -0.0060 0.0010 -5.8063 3.09E-06

a) How many automobiles were tested?

b) Are the conditions for inference satisfied? Explain.

c) Is there evidence of a linear association between the highway mileage and the weight of the vehicles? Test an appropriate hypothesis and state your conclusion.

d) Is the association strong? Explain.

e) What is the equation of the regression line?

f) Create a 95% confidence interval for the slope of the true line.
g) Interpret your interval in this context.

Transcribed Image Text:

Mileage 420 0 Residuals Mileage, Highway + 2000 3000 4000 5000 6000 Weight 5 0 Residuals -5 -10+ 0 + 20 Predicted Mileage 40