問題の解答
検索用コード（LaTeX）
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% 例題A1.1.5：樹形図による数え上げ（One More）★
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6個の文字$a,a,a,b,b,c$から，3個を選んで1列に並べる方法の総数を求めよ．
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% 例題A1.1.5の解答（One More）★
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左から順に，1番目，2番目，3番目とし，樹形図をかく．
8通り
7通り
4通り樹形図より，$8+7+4=19(\text{通り})$
次のように辞書式に並べる方法（辞書式配列）で求めてもよい．
$aaa,aab,aac,aba,abb,abc,aca,acb,baa,bab,bac,bba,bbc,bca,bcb,caa,cab,cba,cbb$
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% 問題A1.1.5：樹形図による数え上げ（One More）★
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大中小の3個のさいころを同時に投げるとき，目の和が$10$になる目の出方は何通りあるか．
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% 問題A1.1.5の解答（One More）★
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左から順に，大，中，小のさいころとし，樹形図をかく．
4通り
5通り
6通り
5通り
4通り
3通り樹形図より，$4+5+6+5+4+3=27(\text{通り})$
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