遇到一题概率题,不懂! 说是supply store stocks 2 sizes of self-stick notepads, each in 4 color: 蓝,绿,黄,粉红,the store packs the notepads in packages that contain either 3 notepads of the same size and same color or 3 notepads of the same size and of 3 different colors. 如果不考虑顺序,how manyy different packages of the types described above are possible? 怎么算呢?