5! or 5^2?

2011-01-28 6:04 am
There are 5 boys and 5 girls in a party. 5 teams are formed with 1 girl and 1 boy to play a game. Ming Oi Mock Q1How many different teams can be formed to play the game?

What is the correct answer?
Thanks.

回答 (4)

2011-01-28 6:26 am
✔ 最佳答案
每個男子可以和1個女子組成隊伍
即是每個男子便有機會可以與5個女子組成隊伍.即是共5個機會
在有5個男子都有機會和5個女子組成隊伍的情況下,機會有:
5x5=25個機會
因為男仔唔可以同男仔一組.所以可能性就會大大減低
就算男仔可以同男仔,女仔可以同女仔

所有既機會就有.C(10抽2)
10!/(2!8!)=45個機會
而5!就=120
同性可以互組都係得45個機會,咁男一定要同女組又何來有120個機會呢?
所以5! 就一定唔係答案.

而答案應該係5^2=25

2011-01-27 22:28:32 補充:
The correct answer is 5^2.
參考: , M1,ME
2011-01-31 10:37 pm
就算男仔可以同男仔,女仔可以同女仔
所有既方法(不是機會)就有 C(10抽2)C(8抽2)C(6抽2)C(4抽2)C(2抽2)

試想像女孩子先排成一行,然後求男孩子排成一行的方法。
2011-01-29 2:35 am
it should be 25(5^2)
2011-01-28 5:21 pm
10 i am guessing


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