Question

Eva is performing an experiment to determine which type if disinfectant kills the most bacteria. She has six plates of the same kind if amount of bacteria. She adds one of five kinds of disinfection to each plate and leaves one plate without any disinfectant as a control.

What role does the test variable (independent variable) play in this experiment?

A. The amount of bacteria killed determined the type of disinfectant used.

B. The type of disinfectant used determined the type of bacteria used.

C. The type of disinfectant determines the amount of bacteria killed.

D. The amount of bacteria killed determines the type of bacteria used.

Answer 1

C.

The independent (test) variable is the type of disinfectant Eva chooses to apply (she manipulates this), and the dependent variable is the amount of bacteria killed (what she measures). The other choices reverse cause and effect or mix up variables.