Permutation
2010-05-30 5:39 pm
There are 3 red balls, 4 white balls and 5 black balls. From this group of balls, find the number of arrangements of " first ball white, second ball white, third ball any color and fourth ball red " (that is WWAR).
回答 (1)
2010-05-30 6:43 pm
✔ 最佳答案
The number of combinations areWhite – white – non red – red and White – white – red – red
= 4 * 3 * 6 * 3 + 4 * 3 * 3 * 2
= 324
2010-05-30 10:44:40 補充：
Correction 4*3*7*3 + 4*3*3*2=324
2010-05-30 10:45:55 補充：
Better to say the number of arrangements (rather than combinations)...
收錄日期: 2021-04-23 23:23:19
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https://hk.answers.yahoo.com/question/index?qid=20100530000051KK00288