Which car make has the smallest average engine size across the five makes?

Which car make has the smallest average engine size across the five makes?

• A. BMW
• B. Toyota
• C. Ford
• D. Vauxhall

Answer: (D)

When you’re comparing across groups, you’re looking for an average—the mean engine size for each car make. The key idea is to calculate the average for every make by adding up all engine sizes for that make’s models and dividing by how many models there are, then compare those five averages to see which is smallest. The make with the smallest mean means its models, on average, use smaller engines. In this dataset, Vauxhall’s models are largely smaller-displacement cars, so its average engine size ends up the lowest. The other makes include more models with larger engines, which pushes their averages higher.

When you’re comparing across groups, you’re looking for an average—the mean engine size for each car make. The key idea is to calculate the average for every make by adding up all engine sizes for that make’s models and dividing by how many models there are, then compare those five averages to see which is smallest. The make with the smallest mean means its models, on average, use smaller engines. In this dataset, Vauxhall’s models are largely smaller-displacement cars, so its average engine size ends up the lowest. The other makes include more models with larger engines, which pushes their averages higher.