问题如下:
A gourmet will rank 12 dishes of a famous restaurant from most delicious to least delicious. To find out the number of possible ranking ways, which principle of counting may be adopted?
选项:
A.Permutation
B.Labeling
C.Multiplication rule
解释:
A is correct. Considering the dishes will be arranged from most delicious to least delicious, the order of the dishes is important. Permutation means rearranging all the members of a set into some sequence or order, so the permutation formula should be adopted.
请问这题为什么是permutation呀?为什么不是factorial呀?