72 lines
1.2 KiB
Plaintext
72 lines
1.2 KiB
Plaintext
ans
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15290
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$(-\infty,3)$
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15291
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$-\dfrac 45$
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15292
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$158$
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15293
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$[1,+\infty)$
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15294
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$10$
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15295
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$1$
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15296
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$\dfrac{2\sqrt{2}}3\pi$
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15297
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$-3$
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15298
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$\dfrac{\sqrt{3}}2$
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15299
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$\dfrac 29$
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15300
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$(-\infty,1)$
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15301
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$10$
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15302
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B
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15303
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B
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15304
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C
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15305
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D
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15306
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(1) $2\times 2$列联表为
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\begin{tabular}{|c|c|c|c|}
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\hline
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& 年龄在$50$周岁以上(含$50$周岁) & 年龄在$50$周岁以下 & 总计\\\hline
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支持态度人数 & $60$ & $180$ & $240$ \\\hline
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不支持态度人数 & $30$ & $30$ & $60$ \\\hline
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总计 & $90$ & $210$ & $300$ \\ \hline
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\end{tabular}. $\chi^2\approx 14.3>3.841$, 有$95\%$的把握认为年龄与所持态度具有相关性; (2) $X\sim \begin{pmatrix}0 & 1 & 2 & 3 & 4 \\ \dfrac 1{81} & \dfrac 8{81} & \dfrac {24}{81} & \dfrac {32}{81} & \dfrac {16}{81}\end{pmatrix}$, $E[X]=\dfrac 83$
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15307
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(1) $-\dfrac\pi 2$或$\dfrac \pi 6$; (2) $1+\dfrac{\sqrt{3}}2$
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15308
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(1) $60^\circ$; (2) $\lambda = \dfrac 32$
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15309
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(1) $2+2\sqrt{2}$; (2) $\lambda+\mu=3$, 证明略; (3) $k=\pm \dfrac 12$, 面积的最大值为$1$
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15310
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(1) 是$L(2)$函数, 理由略; (2) $(\dfrac 12,\dfrac 34]$; (3) $a$的取值范围为$(0,\dfrac 1{10}]$, $M(a)=0.1-\dfrac 12a$
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