Answer:
There is no basis for comparison because the effect of the other variables that are not being studied are not minimized
Explanation:
The rate at which each type of ball bounce are;
Tennis balls;
The height to which the ball is must rebounds ≈ 111 cm
The height from which the ball is dropped = 200 cm
Surface = Steel plate
Basketballs;
The height to which the ball must rebounds ≈ 5.35 inches
The height from which the ball is dropped = 72 inches
Surface = Wooden floor
Squash balls
The height to which the ball must rebounds ≈ 29.5 inches
The height from which the ball is dropped = 100 inches
Steel plate at 70°
Therefore, given that the experimental are performed with different variables of height from which each type of ball is dropped, the surface to which the ball is dropped, the angle of the surface to which the ball is dropped, there is no controlled variable to provide a basis for comparison