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Mathematics Senior High

この問題の2番について、解答とは違うやり方で解いたところ、合っていませんでした。この解き方(写真2枚目)のどこが間違いなんでしょうか??

例題 42 さいころの出る目の最小値 一個のさいころを繰り返し3回投げるとき、次の確率を求めよ。 目の最小値が2以下である確率 目の最小値が2である確率 2004 1個のさいころを繰り返し 3回投げるとき、目の出方は 6通り (1) A: 「目の最小値が2以下」とすると, 余事象Aは「目の CHART & THINKING 「~以上」、「~以下」には 余事象の確率 (1) 最小値が2以下となるのはどのような場合があるかを調べてみよう。 2以下の目が1回 2回 3回出る場合の確率を考え、それらの和を求めればよいのだが, j×2×4°+sC2×23×4+2 実際に計算すると、 6 3 となり、計算が大変。 問題文は「3回のうち少なくとも1回は2以下の目が出ればよい」といい換えることが できるから、余事象の確率が利用できそうだと考えるとよい。 (2) 最小値が2となるのはどのようなときだろうか? 出る目がすべて2以上ならよいのだろうか? 右の図のように、出る目がすべて2以上, すなわち最小値が 以上の場合には、最小値が2でない場合が含まれている とがわかる。 3回のうち少なくとも1回は2の目が出なければならない。 から、余事象の確率が利用できないだろうか? 「最小値が3以上」であるから, Aの起こる確率は 43 4 8 P(A) = -(1) - 2 6³ 6 27 よって求める確率は P(A)=1-P(A)=1- 8 19 27 27 (2) 目の最小値が2以上である確率は よって,(1) から 求める確率は 125 8 61 216 27 216 PRACTICE 42 8 3 53 125 6³ 216 00000 (2) p.313 基本事項 5 最小値が 2以上 最小値が 3以上 最小値が2 if 「3個のさいころを同 「時に投げる」ときの確率と 考えても同じこと。 3以上の目は,3,4,5, 6の4通り。 ←3回とも2以上 6以下の 目が出る確率。 ◆ (最小値が2以上の確率) - (最小値が3以上の確 2章 4 「事象と確率 確率の基本性質

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English Junior High

緑の線を引いているところの意味がわかりません。 その前のTwo girls were swimming in the lake.とその後のOne was the ...からは分かるのですがこの部分だけ日訳わ簡単なものの文脈が理解できません。この話自体ニュージーランド民話ら... Read More

1 ウエヌクが出会った少女 [大阪教育大附高平野 制限時間 1回目: 20分 / 2回目(英文のみ) : 7分 This is the story of "Ue-nuku. Early one morning, before the sun was up, Ue-nuku was walking in the forest. He came to a lake. Two girls were swimming in the lake. They were girls of the sky. They were on earth for a little while. One _)( ) was the Rain-girl. 5 was the "Mist-girl, and ( Ue-nuku did not know who they were, but he knew that they were beautiful. They were so beautiful that 2[ he / how / know / marry / to /to/ wanted] one of them. But while he was watching, the sun came up. When the girls saw it was day, they were frightened. "We must 10 go!" they cried. "We are girls of the mist and rain. If the sun shines on us, we will die." While Ue-nuku watched, the two girls went slowly and softly back up to the sky. That night, Ue-nuku sat alone in his house. He said to himself, "Will I ever see the two girls again? They were so beautiful. I want to 15 marry one of them!" While he was thinking, the door of this house opened and the Mist-girl came in. “Ue-nuku, I have come to stay with you," she said. "But I can only stay at nighttime. When day comes, I must go back up to the sky. If the sun shines on me, I will die." The Mist-girl stayed all that night. Before the sun came up, she said 20 goodbye to Ue-nuku and went to her home in the sky. Ue-nuku did not like this. 4[ he/her/him / stay / to / wanted with all the time. One day, he said to himself, "I will put "mats over the door and window of my house. The Mist-girl will not know day has come. 25 She will think it is still night, and she will stay with me." That night, there were mats over the door and window of the house. "Day has not yet come," said Ue-nuku. "Stay with me." The Mist- )! I'm sure it is day by girl said, "What a 5 ( ) ( now." Ue-nuku said again, "Day has not yet come. Stay with me." Time passed, and the Mist-girl said a third time, "This night is too long. I'm sure it is day now." Before Ue-nuku could stop her, she

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