A consumer group studied two different manufacturers of cars, J and K, to investigate differences in gas
mileage for cars made by the two manufacturers. For a similar type of car, a random sample of 15 cars
from J and a random sample of 12 cars from K were selected, and the gas mileages, in miles per gallon
(mpg), were recorded. The difference in the sample mean gas mileages was used to construct the 90
percent confidence interval (3.5,5.7).
Assuming all conditions for inference were met, which of the following is a correct interpretation of the
interval?
А
The probability is 0.90 that the difference in sample means for gas mileage for the two
car manufacturers is between 3.5 mpg and 5.7 mpg
B
The probability is 0.90 that the population mean difference in gas mileage for the two car
manufacturers is between 3.5 mpg and 5.7 mpg
About 90 percent of the differences in gas mileage for the two car manufacturers are
between 3.5 mpg and 5.7 mpg.
D
We are 90 percent confident that the difference in sample means for gas mileage for the
two car manufacturers is between 3.5 mpg and 5.7 mpg.
E
We are 90 percent confident that the population mean difference of gas mileage for the
two car manufacturers is between 3.5 mpg and 5.7 mpg.