Allstate would like to test the hypothesis that the average age of an imported car on the road is greater than the average age of a domestic car. The following data shows the sample size and the average age of cars for import and domestic cars along with the population standard deviations.
|
Domestic
|
Import
|
|
Sample mean
|
9.4 years
|
10.8 years
|
|
Sample size
|
33
|
36
|
|
Population standard deviation
|
3.2 years
|
2.8 years
|
Define Population 1 as import cars and Population 2 as domestic cars. Construct a 90% (0.10) confidence interval for the difference in population mean and interpret the results.