Bart believes that mice exposed to microwaves will become extra strong (maybe he's been reading too much Radioactive Man). He decides to perform this experiment by
placing 10 mice next to a microwave for 10 seconds. He compared these 10 mice to
another 10 mice that had not been exposed. His test consisted of a heavy block of wood
that blocked the mouse food. He found that 8 out of 10 microwaved mice were able to
push the block away. 7 out of 10 of the non-microwaved mice were able to do the same.
What was one of the constants in this experiment?