ä¸ãä½ çåºæ¬äºä»¶æ»æ°æ±éäºåºè¯¥æ¯n=P(10,5)=30240ï¼æææ¯ä»10å¼ ç¥¨ä¸éæ©5å¼ åæåãä½ çm(A1)=2520ãm(A2)=5040é½æ¯å¯¹çm(A3)æ±éäºï¼åºè¯¥ä¹Pï¼3ï¼2ï¼ï¼èä¸æ¯Cï¼3ï¼2ï¼ï¼åäºä¸¤å¼ ï¼ä½ è¿æ²¡æåé
å¢ï¼m(A3)=Cï¼4ï¼2ï¼ÃPï¼3ï¼2ï¼Ã7Ã6=6Ã6Ã7Ã6=1512æ以æ¦ç为ï¼ï¼2520+5040+1512ï¼/30240=3/10äºãä¸é¢è§£éä½ ä»¬èå¸çæ¹æ³ï¼å设10人å
¨é¨åå®ï¼ååæ³æ»æ°ä¸ºPï¼10ï¼10ï¼=10ï¼åçè¿ç¨ä¸ï¼æ¯åºäºæ¯ä¸ªäººç顺åºå¹¶æ²¡æ太大çå
³ç³»ï¼æ们å¯ä»¥æ第äºä¸ªäººç¼ä¸º1å·ï¼è®©ä»å
éæ¾ç¶ï¼ä»éä¸çå¯è½æ§æ3ç§æ以符åAçåºæ¬äºä»¶æ°ä¸ºï¼3ÃPï¼9ï¼9ï¼=3Ã9ï¼ä¸ãæ¬é¢æ¢ç¶æ¯æ¡ä»¶æ¦çé®é¢ï¼ä½ ä¹å¯ä»¥åèæ¡ä»¶æ¦çéé¢çå
¨æ¦çå
¬å¼ï¼è®¾Bi={å4人ä¸æi人åå¾å
¥åºå¸}åPï¼B0ï¼=ï¼7Ã6Ã5Ã4ï¼/ï¼10Ã9Ã8Ã7ï¼=1/6ï¼Pï¼A|B0ï¼=3/6=1/2Pï¼B1ï¼=ãC(4,1)ÃP(3,1)Ã7Ã6Ã5ã/ï¼10Ã9Ã8Ã7ï¼=1/2ï¼Pï¼A|B1ï¼=2/6=1/3Pï¼B2ï¼=ãC(4,2)ÃP(3,2)Ã7Ã6ã/ï¼10Ã9Ã8Ã7ï¼=10/3ï¼Pï¼A|B2ï¼=1/6Pï¼A|B3ï¼=0æ以P(A)=P(B0)P(A|B0)+P(B1)P(A|B1)+P(B2)P(A|B2)+P(B3)P(A|B3)=1/6Ã1/2+1/2Ã1/3+3/10Ã1/6+0=3/10
追é®å·²ä¸¾æ¥ï¼è¡ä¹±åçé®é¢