Question

The Department of Energy website contains data on 1209 model year 2016 cars and SUVs. Included in the data are the engine size, as measured by engine displacement in liters, and combined city and highway gas mileage, in miles per gallon. Examining the data, one finds that cars with bigger engines tend to have lower gas mileages. In a scatterplot of the engine size and the gas mileage, you expect to see:________

a. very little association.
b. a negative association.
c. a positive association for small engine sizes, and a negative association for large engine sizes.
d. a positive association.

Answer 1

Answer: B. A negative association.

Step-by-step explanation: The form of relationship which may exist between linear variables could either be positive, negative or no relationship. A positive relationship or association exists when an increase or decrease in the independent variable leads to a corresponding increase or decrease in the dependent variable. While no association exists in a scenario whereby there is no change in the dependent variable by varying values in our independent variable. However, in the scenario above, since bigger engines tends to result in a lower gas mileage, this shows that our scatter plot will likely depict a negative association whereby the gas mileage in cars by larger engines are lower while cars with smaller engines exhibit higher gas mileage.