| [ KAIST ] in KIDS 글 쓴 이(By): guest (cortex) <cortex.stat.wisc> 날 짜 (Date): 2001년 12월 10일 월요일 오후 01시 53분 10초 제 목(Title): Re: [질문]� 수학관련질문 sum_{i=0}^n {n \choose i}^2 = {2n \choose n} this is called hypergeometric distribution if you divide both sides by {2n \choose n}. proof. suppose you have n black balls and n white balls... then the number of ways of choosing n balls out of n+n balls. QED. :) |