A bag contains 80 jellybeans, 20 of which are red, 20 are black, 20 are
green, and 20 are yellow. The least number that a blindfolded person
must eat to be certain of having eaten at least one of each color is:
It can't be 60 or fewer for he may have eaten all 60 of only three colors,
so it must be 61, choice a.
(However, in reality we know that the different colors of jellybeans
have different flavors, red is cinnamon, black is licorice, green is
lime, and yellow is lemon, and so the blindfolded person would know
when he had tasted all four of those flavors and he would most likely
eat a lot fewer than 61.) :)
Edwin