Number of ways we can select n objects from a group of m distinct objects is m!/(n!*(m-n)!). Example:" f: t8 S. _3 X' e. O
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 t5 r- e9 U( J
Remember: " Y/ n* R% D/ V" C5 h7 ]' N This does not apply if there are identical objects.
发表于 2012-8-15 12:55:17
