优优班--学霸训练营 > 知识点挑题
全部资源
          排序:
          最新 浏览

          50条信息

            • 1.
              已知随机变量\(X\)服从正态分布\(N(0,σ^{2})\),若\(P(X > 2)=0.023\),则\(P(-2\leqslant X\leqslant 2)\)等于\((\)  \()\)
              A.\(0.477\)
              B.\(0.628\)
              C.\(0.954\)
              D.\(0.977\)
            • 2.
              在对普通高中学生某项身体素质的测试中,测试结果\(ξ\)服从正态分布\(N(1,σ^{2})(σ > 0)\),若\(ξ\)在内\((0,2)\)取值的概率为\(0.6\),则\(ξ\)在\((0,1)\)内取值的概率\((\)  \()\)
              A.\(0.4\)
              B.\(0.2\)
              C.\(0.6\)
              D.\(0.3\)
            • 3.

              经调查,某城市\(2017\)年\(8\)至\(12\)月份中每月的雾霾天数\(y\)\((\)单位:天\()\)与该城市当月汽车出行量\(x\)\((\)单位:万辆\()\)之间的关系如下表:

              月份

              \(8\)

              \(9\)

              \(10\)

              \(11\)

              \(12\)

              月汽车出行量 \(x\)

              \(6\)

              \(5\)

              \(4\)

              \(7\)

              \(8\)

              雾霾天数 \(y\)

              \(17\)

              \(15\)

              \(11\)

              \(20\)

              \(22\)


              \((1)\)用相关系数\(r\)判断\(y\)与\(x\)之间是否具有相关关系\(.(\)若\(|r|\geqslant 0.75\),则认为\(y\)与\(x\)之间有较强的线性相关关系,否则,认为没有较强的线性相关关系,\(r\)精确到\(0.001)\)

              \((2)\)若要使得某月的雾霾天数不超过\(9\)天,那么该月汽车的出行量应控制在多少万辆以内?\((\)答案精确到个位\()\)

              \((3)\)若某个月汽车的出行量在区间\(\left( \bar{x}-3s, \bar{x}+3s\right) \)的右侧,则认为这个月的汽车出行量过大,需从接下来的那个月起对交通进行限行,直至汽车出行量在区间\(\left( \bar{x}-3s, \bar{x}+3s\right) \)内\(.\)已知\(2018\)年\(1\)月该城市汽车出行量为\(11\)万辆,那么该城市\(2\)月份是否要对交通进行限行?试说明理由.

              参考公式:回归方程\(\widehat{y}=\widehat{b}x+\widehat{a}\)中的斜率和截距的最小二乘估计公式分别为:\(\hat {b}= \dfrac{ \sum\nolimits_{i=1}^{n}{x}_{i}{y}_{i}-n \bar{x} \bar{y}}{ \sum\nolimits_{i=1}^{n}x_{i}^{2}-n{ \bar{x}}^{2}},\hat {a}= \bar{y}-\hat {b} \bar{x} \)相关系数\(r= \dfrac{ \sum\nolimits_{i=1}^{n}{x}_{i}{y}_{i}-n \bar{x} \bar{y}}{ \sqrt{\left( \sum\nolimits_{i=1}^{n}{{x}_{i}}^{2}-n{ \bar{x}}^{2}\right)\left( \sum\nolimits_{i=1}^{n}{{y}_{i}}^{2}-n{ \bar{y}}^{2}\right)}} \)

              参考数据:\(\sum\limits_{i=1}^{5}{{{x}_{i}}}{{y}_{i}}=537,\sum\limits_{i=1}^{5}{x_{i}^{2}}=190,\sqrt{(\sum\limits_{i=1}^{5}{x_{i}^{2}-5{{\overline{x}}^{2}})(\sum\limits_{i=1}^{5}{y_{i}^{2}-5{{\overline{y}}^{2}})}}}=27.2\),\(s=\sqrt{\dfrac{1}{5}\sum\limits_{i=1}^{5}{{{({{x}_{i}}-\overline{x})}^{2}}}}\approx 1.4\).

            • 4.
              已知随机变量\(ξ~B(n,p)\),且\(E(ξ)=12\),\(D(ξ)=2.4\),则\(n\)与\(p\)的值分别是\((\)  \()\)
              A.\(15\),\( \dfrac {4}{5}\)
              B.\(18\),\( \dfrac {2}{3}\)
              C.\(20\),\( \dfrac {3}{5}\)
              D.\(24\),\( \dfrac {1}{2}\)
            • 5.
              已知随机变量\(X\)服从正态分布即\(X~N(μ,σ^{2})\),且\(P(μ-σ < X\leqslant μ+σ)=0.6826\),若随机变量\(X~N(5,1)\),则\(P(X\geqslant 6)=(\)  \()\)
              A.\(0.3413\)
              B.\(0.3174\)
              C.\(0.1587\)
              D.\(0.1586\)
            • 6.
              设\(X~N(500,60^{2})\),\(P(X\leqslant 440)=0.16\),则\(P(X\geqslant 560)=(\)  \()\)
              A.\(0.16\)
              B.\(0.32\)
              C.\(0.84\)
              D.\(0.64\)
            • 7.

              已知随机变量\(X\)\(~N(2,\)\(s\)\({\,\!}^{2})\),若\(P\)\((\)\(X\)\( < \) \(a\)\()=0.32\),则\(P\)\((\)\(a\)\(\leqslant \)\(X\)\( < 4-\)\(a\)\()=\)________.

            • 8. 已知随机变量\(X\)服从正态分布\(N(0,σ^{2})\),若\(P(X > 2)=0.023\),则\(P(-2\leqslant X\leqslant 2)\)等于\((\)  \()\)
              A.\(0.477\)
              B.\(0.628\)
              C.\(0.954\)
              D.\(0.977\)
            • 9. 设随机变量\(ξ\)服从正态分布\(N(1,σ^{2})\),若\(P(ξ < 2)=0.8\),则\(P(0 < ξ < 1)\)的值为\((\)  \()\)
              A.\(0.2\)
              B.\(0.3\)
              C.\(0.4\)
              D.\(0.6\)
            • 10. 已知随机变量\(X\)服从正态分布\(N(0,δ^{2})\),且\(P(-2\leqslant x\leqslant 0)=0.4\),则\(P(x > 2)=\) ______ .
            0/40

            进入组卷