At a candy factory, one barrel of highly experimental fluorescent pink M&Ms has accidentally been emptied into the packing machine. If there were four barrels of other colors also in the machine, what is the probability that a package of five M&Ms from the resulting batch contains four pink ones? (Hint: assume that the machine mixes up all of the different colors of candy evenly so that the candies going into the package are chosen as if each is sampled).