Number of ways we can select n objects from a group of m distinct objects is m!/(n!*(m-n)!). Example:1 j5 i/ f8 ~1 `" P5 n, o4 D, J+ n
Number of possible ways to pick 4 oscar nominations from a list of 50 movies is 50!/(4!*(50-4)!)=50!/(4!*46!)=50*49*48*47/24=2303003 o/ u# h5 M9 P+ [: M: S
Remember: 8 I6 D. Q: z/ @, ]! ?3 C This does not apply if there are identical objects.
发表于 2012-8-15 12:55:17
