Read the description of the relationship between the following quantitative variables. Identify each relationship as having a positive association, a negative association, or no association.
Students who study longer tend to earn better grades on their statistics exams. The direction of this relationship is .:positive
A student asks a random sample of 10 of her classmates how tall they are and how many text messages they sent over the past 24 hours. The direction of this relationship is .:no association
People who exercise more frequently tend to have a lower resting heart rate than those who do not exercise as frequently. The direction of this relationship is .:negative