Question

liz’s math test included a survey question asking how many hours students spent studying for the test. the scatter plot and trend line plots the relationship between how many hours students spent studying and their score on the test. assuming the line is correct, what does the line’s slope of 15 mean? choose 1 answer: a) on average, students who didn’t study at all got scores of about 15 on the test. b) if one student studied for one hour more than another student, the student who studied more got exactly 15 more points on the test. c) on average, studying for one extra hour was associated with a 15 point improvement in test score. d) on average, studying for 15 extra hours was associated with a 1 point improvement in test score.

Explanation:

• Option A: The y - intercept (not the slope) represents the score when study time is 0. So A is incorrect.
• Option B: A trend line shows an average association, not an exact number of points. So B is incorrect as it says "exactly".
• Option C: The slope of a trend line in a scatter plot of study time (x - variable) and test score (y - variable) represents the average change in the y - variable (test score) for a one - unit change in the x - variable (study time). A slope of 15 means that for each additional hour of study (a one - unit increase in x), the test score (y) increases by 15 on average. This matches the description of the slope's meaning.
• Option D: A slope of 15 means 15 points per hour, not 1 point per 15 hours. So D is incorrect.

Answer:

C. On average, studying for one extra hour was associated with a 15 point improvement in test score.