Question

two friends want to decide whose car gets the best gas mileage. a cars gas mileage is the number of miles a car can go for each gallon of gas it uses. the friends decide to fill the first tank of gas in car a and the second tank of gas in car b. they will use the same amount and type of gas and compare how far each car travels before the tank reaches empty. why is it important that the two cars get the same type of gas?
a. by using the same type of gas, the friends can learn which type of gas gets the best mileage.
b. if the cars do not get the same type of gas, the friends cannot find out which car model has the best mileage.
c. it is not important for both cars to have the same type of gas because they are not testing which type of gas gets the best mileage.
d. by using the same type of gas, the friends can learn both which car model gets the best mileage and which type of gas gives the best mileage.

Explanation:

To compare gas mileage, variables like gas type should be controlled. If different gas types are used, it's hard to isolate the effect of the car model on mileage. Using the same gas type allows a fair comparison of car models' mileage.

Answer:

A. By using the same type of gas, the friends can learn which type of gas gets the best mileage.