某站1961~1979年各月径流量列于表2-11-1,试结合表2-11-2求P=10%的设计丰水年、P=50%的设计平水年、P=90%的设计枯水年的设计年径流量?表2-11-1 某站年、月径流量表( m3/s )年份月 平 均 流 量 Q月 （m3/s）年平均流量Q年（m3/s）34567891011121261～6262～6363～6464～6565～6666～6767～6868～6969～7070～7171～7272～7373～7474～7575～7676～7777～7878～7916.57.258.2114.712.93.209.913.909.5213.9.4512.216.35.083.2815.43.2822.422.8.6919.517.715.74.9812.526.629.17.915.611.524.86.1011.738.55.4837.143.16.326.419.841.67.1512.915.213.533.215.533.941.24.337.141.611.858.17.26.124.630.450.716.234.613.625.443.37.825.30.722.816.457.417.123.94.637.157.355.2019.45.556.906.1225.410.542.712.724.23.4010.231.714.410.62.467.509.624.8710.42.285.5513.43.583.586.557.308.303.4519.25.8614.312.44.026.813.209.107.482.132.004.272.671.673.523.656.504.925.756.563.846.264.841.862.073.462.971.273.2710.52.231.572.544.968.752.794.414.553.698.511.982.671.983.425.302.181.628.211.931.821.843.184.521.764.532.594.677.302.472.731.902.922.671.541.179.032.761.422.682.357.961.305.591.635.167.541.874.202.352.481.796.45.998.351.411.214.253.884.102.238.471.766.263.1221.62.0313.21.621.803.873.068.485.302.369.003.573.808.768.895.2111.15.5611.97.7810.9.6414.44.737.8710.410.210.912.610.315.17.2411.317.78.4216.9表2-11-2 P—III型频率曲线Kp值表

设 X sim N(0,1), Y sim x^2(n)，且 X, Y 相互独立，则 (X)/(sqrt(Y)) sqrt(n) ~A. t(n)B. t(n-1)C. F(1,n)D. F(n,1)

1． 设两个相互独立的随机变量 X 和 Y 的方差分别为 4 和 2，则随机变量3X－2Y 的方差是A. 8B. 16C. 28D. 44

在平炉炼钢中，由于矿石与炉气的氧化作用，铁水的总含碳量在不断降低，一炉钢在冶炼初期总的去碳量Y与所加的两种矿石的量X1、X2及熔化时间x，(单位：5min)有关．经实测某号平炉的49组数据如表4.4.1所示．求Y对X1，X2，X3的线性回归方程，检验回归方程和回归系数的显著性．如有不显著的变量，请剔除之并求剔除不显著的变量之后的回归方程． 表4.4.1某号平炉的49组实测数据 编号 x1(槽) x2(槽) x3(5min) y(t) 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849 2751213367030860371660940929126120540641045965582741034 189143201217582316184142l1412016150617016651372412152016174141381381161381051715 504046436440643937556049505l51515648455240324744393951414761374945424848363651541004463555045406472 4.33023.64854.48305.54685.49703.11255.11823.87594.67004.95365.00605.27015.37725.48494.59605.66456 07953.21945.80764.73064.68053.12722.61043.71743.89462.70665.63145.81525.13025.39104 45334 65694.52124.86505.35664.60982.38153.87464.59195.15885.43733.99604.39704.06222.29054.71154.53105.36376.0771

1、设总体X服从参数为N和p的二项分布，X_(1),X_(2),...,X_(n)为取自X的样本，试求参数N和p的矩估计量与p的最大似然估计量。

X1,X2,···,Xn是来自正态总体 sim N(0,1) 的样本,X,S^2分别为样本均值与样-|||-本方差,则下列各式正确的是 () .-|||-(A) overline (X)sim N(0,1) ; (B) overline (X)sim N(0,1) ;-|||-(C) sum _(i=1)^n({X)_(i)}^2sim (chi )^2(n) : (D) overline (X)/Ssim t(n-1) .

用两种方法检查某疾病患者120名,甲法检出率为60%,乙法检出率为50%,甲,乙法一致的检出率为35%,问两种方法何者为优()。A. 甲法优于乙法B. 乙法优于甲法C. 不能确定D. 甲,乙法一样

30.设X1,X2,X3,X4是来自标准正态总体的样本,则 ({X)_(1)}^2+({X)_(2)}^2+({X)_(3)}^2+({X)_(4)}^2 服从的分-|||-布是() ()-|||-A.t(4)B.N(0,4^2)C.x^2(4)D.F(1,4)

相关系数度量的是自变量与因变量不对称的因果关系。（）A. 对B. 错

5.7 一本书排版后一校时出现错误数X服从正态分布N(200，400)，试求：(1)出现错误数不超过230的概率。(2)出现错误数在190~210之间的概率。