Question

the passage below describes an experiment. read the passage and then follow the instructions. richard noticed that some of the footballs his team used during practice were not fully inflated. he wondered whether fully inflated footballs would travel farther than footballs with a lower air pressure. to find out, richard collected 20 standard footballs. he fully inflated ten of them to an air pressure of 13 pounds per square inch. he inflated the remaining ten to an air pressure of 10 pounds per square inch. richard used a football launcher to launch a ball across a football field. he measured the distance the football traveled and then launched the next ball. richard repeated this with all 20 balls. complete the sentence. in this experiment, the air pressure in the footballs was a dependent variable an independent variable

Explanation:

In an experiment, the independent variable is what the experimenter manipulates. Here, Richard changes the air - pressure in the footballs (13 psi and 10 psi). The dependent variable would be the distance the footballs travel. Since the air - pressure is being changed by the experimenter, it is the independent variable.

Answer:

an independent variable