Why is marginal change so Important in making economic decisions?

Ascientist performs an experiment where she measures the mass of a piece of metal, pours acid onto the metal, washes the metal, and then re-measures the mass of the metal. the scientist repeats the experiment several times, each time increasing the amount of acid used. the dependent variable in the experiment is the: initial mass of the metal final mass of the metal amount of acid used washing the metal

The people are the source for any and all governmental power in the united states

How was the age discrimination in employment act amended in 1986?