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数学 高校生

⑵なぜ1になるの?

452 本 例題 65 確率密度関数と確率 (1) 確率変数Xの確率密度関数が右の f(x) で与えられているとき, 次の確 率を求めよ。 (ア) P(0.5X1 (イ) P(-0.5≦x≦0.3) 00000 f(x)=(1+x (05*51) x+1(-1≦x≦0) (2) 確率変数 X のとる値xの範囲が 0≦x≦3 で,その確率密度関数が f(x)=k(4-x)で与えられている。このとき,正の定数kの値を求めよ。 CHART & SOLUTION 確率密度関数と確率 (確率の総和)=1⇔ (全面積)=1 (1) 連続型確率変数Xの確率密度関数f(x) において P(a≤x≤b) p.450 基本事項 =(曲線y=f(x) とx軸, および2直線x=a, x=6で囲まれた部分の面積) (2) 確率変数Xのとる値xの範囲が 0≦x≦3 であるから 解答 P(0≦x≦3)=1 すなわち Sk(4-x)dx=1 (1) (ア) P(0.5≦x≦1)=1/2×0.5×0.5=0.125 (イ) P(-0.5≦x≦0.3) =1-P(-1≦x≦ -0.5) -P(0.3≦x≦1) 1/12/ (ア) 日本 例題 6 確率変数X 関数f(x)が を求めよ。 (1)確率P( L CHART & (1)確率密度関 → 前ページ BI → (1), (2), (3) Sx"dx (1) P(3≦X まず, y=f(x) のグラ フをかく。 ← (全面積)=1 を利用。 注意 確率を表す面積を積 (2)E(X)= =1-10.5・0.5-- -0.7・0.7=1-0.125-0.245=0.63 2 (イ) YA 分で求めることが多いが, 三角形の面積と考えて計 算すると早い。 1 10.5 --- 0.5 1 0.7 (3) V(X)= -1 0 0.5 1 x -1-0.50 0.3 1 x YA Sok 4k (2)条件から k(4-x)dx=1 Sk(4-x)dx= k[4x-x²-15 kであるから 2 Jo k 15 -k=1 2 よって 2 0 34 k=- 15 PRACTICE 65° 確率変数Xのとる値xの範囲が 0≦x≦1 で, その確率密度関数がf(x)=α(3-x) で与えられている。 このとき,正の定数αの値を求めよ。 また, 確率 P(0.3≦x≦0.7) を求めよ。 って 11 PRACTIC ((1) 確率 f(x) で 数αの他 (2) (1)の

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英語 高校生

英語長文問題です (1)イ?ウ? (2)ウ (3)イ (4)ア 解いてみたのですが(1)が分かりませんでした (2)(3)(4)もあっていますか?

14 Paraphrase Rapid Reading [速読 目標解答時間12分 ] 鶴と亀の物語から得られる教訓は何でしょうか。 Listening EX ON の 船 1 Once there were two cranes and a tortoise who lived by a lake and became good friends. They played together all day long, sunning themselves on the sand and swimming in the lake. They were very happy and wanted to be together forever. 2 But that year there was a drought*. For five months, no rain fell at all. The rivers and the land cracked. Each day, the little lake where the tortoise and cranes dried up, lived became smaller and smaller. 3 One day the two cranes flew into the air to see how things were, and came back in the evening saying, "Tortoise, everyone is moving to the Heavenly Lake. I think we should move too. If we stay here, we'll die of hunger and thirst." 13 end sky gra 14 to O P 1 5 The tortoise shut his little eyes and cried. "Oh, you can fly or hurry as fast as you 10 get to the Heavenly Lake. But I can neither fly nor walk fast. Within three days I will be nothing but an empty shell! We have been friends for so long. Please don't leave want, and me behind." 5 The tortoise cried so much that the cranes, unable to hold their own tears back, did not have the heart to leave him behind. So they decided to stay at the lake with the 15 tortoise for a while. Perhaps the rain would come in a few days. 6 But the weather did not change. Clear stars dotted the sky at night, and the sun was they thought hot and cruel el by day. The little lake was nearly dry. The cranes said again they must go. The tortoise knew that he could not keep them there any longer, so he pleaded* with them, saying "We have been friends for so long! Can't you think of a way to 20 take me along?" 7 They thought long and hard. After some time the cranes said, "Tortoise, we have a plan, but it will be difficult." 18 The tortoise asked eagerly, "What is it? What is it?" "We'll hold two ends of a stick in our beaks*, and you can hold on to the middle with 25 your mouth. Then we can fly, carrying you between us. What do you think of the idea?” 10 The tortoise was so happy that he nearly jumped. "Yes, yes! That's a good idea! Let's start at once!" 11 The cranes were very happy, too, but they had to give him a warning. "You must be NOTES drought : 干ばつ plead : 嘆願する 32 UNIT 8 beak (鳥の) くちばし )( ).no パート ごとの 音声 ON

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