Final answer:
Data sets or plots that could have a regression line with a negative slope are a straight line with negative slope and variables with a strong negative linear relationship.
Step-by-step explanation:
A regression line with a negative slope indicates a negative relationship between two variables, meaning that as one variable increases, the other decreases. Based on the options provided, the correct choices for data sets or plots that could have a negative slope are:
- a. It is a straight line with negative slope.
- 10. The X and Y variables have a strong negative linear relationship.
These scenarios depict a direct inverse correlation between the two variables. For instance, the classic example of price and quantity demanded demonstrates this; as price goes up (x increases), the quantity demanded decreases (y decreases).