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標題:
Permutation & Combination
Find the no. of ways to divide 6 boys into 3 groups : (a) with 2 boys in each group. (b) 4 boys in one group, 1 each in the other 2 groups.
最佳解答:
(A) the combination=(6C2 x 4C2)/3!=15 如果你問點解要除3! 原因係: 假設6個男仔ABCDEF 我先揀左AB 再揀CD 再揀EF 另1個可能係我先揀CD再揀AB再揀EF 你有無發現依2個揀法其實係一樣? 但我地係6C2 x 4C2既時候就會咁樣計重覆左,所以要除3! (B) the combination=(6C4 x 2C1)/2!=15 or simply 6C4=15 要除2!既原因同上。
其他解答:
Permutation & Combination
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發問:Find the no. of ways to divide 6 boys into 3 groups : (a) with 2 boys in each group. (b) 4 boys in one group, 1 each in the other 2 groups.
最佳解答:
(A) the combination=(6C2 x 4C2)/3!=15 如果你問點解要除3! 原因係: 假設6個男仔ABCDEF 我先揀左AB 再揀CD 再揀EF 另1個可能係我先揀CD再揀AB再揀EF 你有無發現依2個揀法其實係一樣? 但我地係6C2 x 4C2既時候就會咁樣計重覆左,所以要除3! (B) the combination=(6C4 x 2C1)/2!=15 or simply 6C4=15 要除2!既原因同上。
其他解答:
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