These website should answer more than you ask...
http://en.wikipedia.org/wiki/Poker_probability
See: Frequency of 5-card poker hands
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Specifically for your question:
No 啤 [ABCDE] ... Prob = 0.50117739
1啤 [AABCD] ... Prob = 0.42256902
2啤 [AABBC] ... Prob = 0.04753901
3條 [AAABC] ... Prob = 0.02112845
Full House [AAABB] ... Prob = 0.00144057
4條 [AAAAB] ... Prob = 0.00024010
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Can explain more if you want... ^_^
2007-12-10 10:27:04 補充:
i think the question asking is getting 2張 3張 4張 啤的概率,
rather than 抽出2張、3張及4 張啤牌有啤的概率
good answer anyway