I need to know answers to all three please and fast 18. If you were conducting an experiment, you would change only one thing,
A. to support your hypothesis.
C. to know exactly what caused the results.
B.
because there is only one constant in an
D.
experiment.
to simplify the experiment so results are more
understandable.
_19. A hypothesis is
A.
a proven statement.
C. a definite answer to a given problem.
B. a concluding statement.
D. a testable possible explanation of an observation.
20. A controlled experiment
A. introduces bias.
C. tests several variables at once.
B.
tests only one variable and is free of bias.
D.
changes no variables.