Johnny 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, Johnny 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. Johnny 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. Johnny repeated this with all 20 balls.

•What is his independent variable?

•What is his dependent variable?

•What is his control?