Mack Trucks decides to conduct an experiment to determine if a new oil additive actually results in increased fuel efficiency. They find a lab that contains 50 engines that are exactly alike. Mack randomly divides the 50 engines into two groups an experimental group (which has the new oil additive)and the control group (which does not have the new oil additive). They pour the exact same amount of fuel into all 50 engines and time how long each engine runs. Afterward, they average the length of time run by the 25 engines in the control group versus the 25 engines in the experimental group. Which of the following represents the experimental design in this study?
A) X 01
B) (R) 01 X 02
(R) 03 04
C) 01 X 02
D) (R) 01 X 02
(R) 03 D 04
E) (R) 01 02
(R)03 D 04

Which of the following represents the experimental design in this study?

A) X 01

Explanation:

The correct answer is A because this experiment has only one dependent variable:  the increased fuel efficiency by a new oil additive.

The symbol that represents the measurement of the dependent variable is "0" and option A is the one measuring only one dependent variable whereas options:

B) (R) 01 X 02 (R) 03 04

C) 01 X 02

D) (R) 01 X 02 (R) 03 D 04

E) (R) 01 02 (R)03 D 04

measure 2 or more dependent variables.

The correct option is option A: X 01

Explanation:

As the key parameter is the addition of additives on the fuel efficiency thus this indicates that there is only one variable which is the focus of the study and thus the correct option is option A.

Option B,C,D are not true as it involves more than the required data variables.