PSAT Math Multiple-Choice Question 211: Answer and Explanation

Question: 211

A student looked at the graph above and determined based on the data that spending more money per student causes the gross domestic product (GDP) to increase. Which of the following statements is true?

• A. The student is correct; the data shows that increased spending on students causes an increase in the GDP.
• B. The student is incorrect; the data shows that having a higher GDP causes an increase in the amount of money a country spends on students.
• C. The student is incorrect; there is no correlation and, therefore, no causation between GDP and expenditures on students.
• D. The student is incorrect; the two variables are correlated, but changes in one do not necessarily cause changes in the other.

Correct Answer: D

Explanation:

D

Difficulty: Medium

Category: Problem Solving and Data Analysis/Statistics and Probability

Getting to the Answer: The two variables are certainly correlated—as one goes up, the other goes up. A linear regression model would fit the data fairly well, so you can eliminate (C). The spending is graphed on the x-axis, so it is the independent variable and therefore does not depend on the GDP, graphed on the y-axis, so you can eliminate (B) as well. The data does show that as spending on students increases, so does the GDP, but this is simply correlation, not causation. Without additional data, no statements can be made about whether spending more on students is the reason for the increased GDP, so (D) is correct.