7.设某两个工厂的每日碳排放量X,Y相互独立且分别服从N(μ,1)和N(μ ,3),各观测两个工厂36日-|||-的碳排放量,记样本均值分别为x,F,(1)计算概率 (|overline (X)-overline (Y)|gt 1) ;(2)求方差 [ ((overline {X)-overline (y))}^2] .

某站1958~1976 年各月径流量列于下表,试结合下表求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?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(m3/s)3月4月5月6月7月8月9月10月11月12月1月2月1958-195916.522.043.017.04.632.464.024.841.982.471.8721.611.91959-19607.258.6916.326.17.157.506.811.862.672.734.202.037.781960-19618.2119.526.424.67.359.623.202.071.981.902.3613.210.01961-196214.717.719.3830.45.204.879.103.463.422.922.481.629.641962-196312.915.741.650.719.410.47.482.975.302.671.791.8014.41963-19643.204.987.1516.25.552.282.131.272.181.546.453.874.731964-19659.9112.512.934.63.905.552.003.271.621.170.993.067.871965-19663.9026.615.213.66.1213.44.2710.58.219.038.358.4810.41966-19679.5229.013.525.425.43.582.672.231.932.761.415.3010.21967-196813.017.933.243.010.53.581.671.571.821.421.212.3610.91969-197012.211.533.925.012.77.303.654.963.182.353.883.5710.31970-197116.324.841.030.724.28.306.508.754.527.964.103.8015.11971-19725.086.1024.322.83.403.454.922.791.761.302.238.767.241972-19732.2811.737.116.410.219.25.754.414.535.598.478.8911.31973-197415.3438.541.657.731.75.866.564.552.591.631.765.2117.71974-19753.285.4811.817.114.414.33.843.594.676.166.2611.18.421975-197622.437.158.023.910.612.46.268.517.307.543.125.5616.9

正偏态分布:A. 峰偏左,长尾向右延伸B. 两者均无C. 峰偏右,长尾向左延伸D. 两者均有

四、我国26个城市1~12月空气质量综合指数月均值如下表4所示,试月份为横坐标,绘制折线图。 (10分)表4 26个城市1~12月空气质量综合指数表空气质量综合指数123456789101112A13.904.163.233.203.202.842.202.142.536.124.286.39B13.803.923.273.523.703.132.242.792.25.094.025.13C16.004.584.153.404.383.403.303.433.314.494.546.09D1..203.844.223.484.053.243.293.203.484.444.075.12E26.509.226.935.626.706.545.075.086.258.307.251..22F10.405.225.384.634.564.893.863.803.925.475.155.39G15.507.786.925.083.833.383.783.884.585.763.798.00H8.804.296.114.653.383.363.293.543.623.474.284.79I15.207.395.292.933.033.163.263.433.883.965.094.35J9.703.175.243.143.093.334.133.112.263.264.283.79K1..404.063.283.303.082.561.671.882.653.794.895.42L1..905.656.814.423.823.523.423.653.274.713.855.89M6.202.853.693.882.592.721.782.342.993.042.933.28N8.102.453.662.872.662.691.442.212.803.452.563.85O7.502.333.332.832.972.511.862.393.344.763.815.27P6.302.172.472.762.762.402.012.372.012.772.262.72Q16.206.214.524.484.965.014.063.794.555.654.786.44R12.504.304.384.034.053.282.493.094.435.684.776.60

3.设总体 sim N(12,(2)^2), X1,X2,···,X5为来自正态总体X的样本,求:-|||-(1) max{ {x)_(1),(x)_(2),... ,(x)_(5)} gt 15} ;-|||-(2) min{ {X)_(1),(X)_(2),... ,(X)_(5)} gt 10} .

(13)(2010年,一)设总体X的分布为:-|||-X 1 2 3-|||-p https:/img.zuoyebang.cc/zyb_2a76612f05065171cccaed4e98b26d93.jpg-theta theta -(theta )^2 θ^2-|||-其中 theta in (0,1) 未知,以N1表示来自总体X的简单随机样本(容量为n)中等于i的-|||-个数 (i=1,2,3) ,试求常数a1,a2 ,a3使 =sum _(i=1)^3(a)_(i)(N)_(i), 为θ的无偏估计量,并求T-|||-的方差.

1.（单选题，5.0分）设随机变量X服从正态分布N(μ，σ²），则Y=(X-μ)/(σ)服从____分布

设总体 X 的概率密度函数为 f(x)= leqslant xleqslant theta +dfrac {1)(2) 0,else .的矩估计和极大似然估计。

2、若总体X服从参数为θ的指数分布，X_(1),X_(2),...,X_(n)为X的样本，则参数θ的矩估计量hat(theta)=A. (1)/(overline(X))B. overline(X)C. 1D. B_(2)

3【填空题】设来自总体的一个样本观察值为：2.1，5.4，3.2，9.8，3.5，则样本均值为____样本方差为____。