Answer:
Positive correlation
Step-by-step explanation:
Two variables are said to be correlating if they have some kind of relationship - that is, if the value of one variable increases/decreases as the other variable increases or decreases.
More specifically, there are three types of correlation:
- Positive correlation: this occurs if, as the value of one variable increases, the value other variable increases too
- Negative correlation: this occurs if, as the value of one variable increases, the value of the other variable decreases
- No correlation: this occurs if, as the value of one variable increases, the other variable doesn't show any precise trend
In this problem, we are studying the following two variables:
- Number of hours a plane is flying (t)
- Number of miles flown (d)
The two variables are related by the equation

where v is the speed of the plane (in miles per hour).
As we can see from this equation, there is a direct proportionality between the two variables: therefore, as t increases, d increases, and so we can say there is a positive correlation.