Inertial weight (in tons) and fuel economy (in mi/gal) were measured for a sample of seven diesel trucks. The results are presented in the following table. (From "In-Use Emissions from Heavy-Duty Diesel Vehi- cles," J. Yanowitz, Ph.D. thesis, Colorado School of Mines, 2001.)
|
Weight
|
Mileage
|
|
8.00
|
7.69
|
|
24.50
|
4.97
|
|
27.00
|
4.56
|
|
14.50
|
6.49
|
|
28.50
|
4.34
|
|
12.75
|
6.24
|
21.25 4.45
a. Construct a scatterplot of mileage (y) versus weight (x).
b. Compute the least-squares line for predicting mileage from weight.
c. If two trucks differ in weight by 5 tons, by how much would you predict their mileages to differ?
d. Predict the mileage for trucks with a weight of 15 tons.
e. What are the units of the estimated slope βˆ1 ?
f. What are the units of the estimated intercept βˆ0 ?