The following is the results of a regression analysis of vehicle fuel efficiency (MPG) and vehicle weight (in thousands of pounds)
| Vehicle |
Count |
Mean |
StdDev |
| MPG |
50 |
25.0200 |
4.83394 |
| wt/1000 |
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 |
less than or equal to 0.0001 |
| Weight |
-8.21362 |
0.6738 |
-12.2 |
less than or equal to 0.0001 |
a) Create a 95% confidence interval for the slope of the regression line and explain what the interval means
b) Create a 95% confidence interval for the average fuel efficiency among cars weighing 2,500 pounds and explain what the interval means