Questions: Suppose that the P in this equation refers to the price Julie is willing to pay for an additional magazine, and the Q refers to the number of magazines to which Julie subscribes. Read the following statement carefully: "The more magazines Julie subscribes to, the less she is willing to pay for an additional magazine." Which of the following best summarizes the pattern of causality suggested by this statement? A change in Q causes a change in P. A change in P causes a change in Q. The relationship between P and Q is not a causal relationship.

The answer is the first one: A change in \( Q \) causes a change in \( P \).

Explanation:

• The statement "The more magazines Julie subscribes to, the less she is willing to pay for an additional magazine" suggests that as the quantity of magazines (\( Q \)) increases, the price (\( P \)) Julie is willing to pay for an additional magazine decreases.
• This indicates a direct causal relationship where the change in the number of magazines (\( Q \)) Julie subscribes to leads to a change in the price (\( P \)) she is willing to pay for an additional magazine.
• Therefore, the correct summary of the pattern of causality is that a change in \( Q \) causes a change in \( P \).