Martin Motors has in stock three cars of same make and model. The president would like to compare the gas consumption of three cars (labeled car A, car B, and car C) using four different kinds of gasoline. For each trial, a gallon of gasoline was added to empty tank, and the car was driven until it ran out of gas. The following table shows the number of miles driven in each trial.
|
Types of Gasoline
|
Distance (miles)
|
|
Car A
|
Car B
|
Car C
|
|
Regular
|
22.4
|
20.8
|
21.5
|
|
Super regular
|
17.0
|
19.4
|
20.7
|
|
Unleaded
|
19.2
|
20.2
|
21.2
|
|
Premium unleaded
|
20.3
|
18.6
|
20.4
|
Using the .05 level of significance:
a. Is there a difference among kinds of gasoline?
b. Is there a difference in cars?