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1、第二章第二章2.12.1 判断题:(1)错;(2)错;(3)对;(4)错;(5)错;(6)错;(7)错;(8)错;(9)对;(10)对;(11)错;(12)错;(13)错。2.32.3 选择题:(1)b;(2)b;(3)d;(4)c;(5)c。2.72.7(1)抽样分布:33.674.3355.676.3371/101/102/102/102/101/101/10(2)期望为 5,方差为 4/3(3)抽样标准误=1.155(4)抽样极限误差=1.96*1.155=2.263(5)置信区间=(5.67-2.263,5.67+2.263)=(3.407,7.933)。若区间两端只考虑抽样分布的可能
2、性取值,则可得该抽样分布作为离散分布的置信区间为3,7第三章第三章3.13.1判断题是否为等概率抽样:(1)是;(2)否;(3)是;(4)否。3.23.2(1)Y 1Yi 5.5N1(YiY)2 6.25N2S21(YiY)2 8.33N 1(2)样本:(样本:(2,52,5)(2,62,6)(2,92,9)(5,65,6)(5,95,9)(6,9)(6,9)Ey13.5 45.55.577.5 5.561(4.58 24.50.58 4.5)8.336E s2 3.33.3(1)yi1682yi11826621 f130/17500.03276n30y 1682/3056.0671n1 n2
3、1182663050.067222s(y y)yny826.271iin1i1n1i13012vy1 f2s 0.03276826.271 27.07nse(y)vy5.203 tse(y)1.965.20310.19895%置信度下置信区间为(56.067-10.198,56.067+10.198)=(45.869,66.265).因此,对该校学生某月的人均购书支出额的估计为 56.07(元),由于置信度 95%对应的t 1.96,所以,可以以 95%的把握说该学生该月的人均购书支出额大约在45.8766.27 元之间。(2)易知N=1750,n=30,=8,t=1.96p n181 f13
4、0/1750 0.2670.03389n30n1301pq p(1 p)0.267(10.267)0.1957v(p)(1 f)pq110.033890.957 0.08144 0.0167n12n230P的 95%的置信区间为:(1 f)pq1pt 0.2671.960.081140.0167(0.0907,0.4433)n12n Np 467.25 467,其 95%的置信区间为:则N1的估计值为N11750(0.0907,0.4433)(159,776)t2q1.962(10.267)1054.64(3)n02p0.120.267可得最少的样本量:n n01054.64 658.2948
5、 659。n011054.641111750N3.43.4(1)N 200000n 70n1 61 f11 0.01449n 1n 1701该地区拥有私人汽车的比例估计:p n16 0.086n70q 1 p 10.0860.914pq 0.0860.9140.0786因而比例估计的标准差:se(p)(2)t=1.96 5%t2pq1.9620.0786120.79 121n020.052(1 f)pq0.014490.0860.914 0.0338n1由于 N 很大,最少的样本量n n0 n0121。n011N3.53.5已知P10.08 Q10.92P20.05 Q2 0.95V 0.05
6、2CV 0.05要得到相同的标准差 0.05,则所需的样本量由n0PQ得:V(P)n010.080.920.050.952 29.44 30n1900.0520.052Q得:CV2(P)P要得到相同的变异系数 0.05,则所需的样本量由n0n010.920.952 4600n 7600。00.0520.080.0520.05第四章第四章4.3(1)根据题中所给的数据,可以得到以下相关结果h123合计nh10101030Nh2564201688443Wh0.30330.49760.19911.0000fhyhWhyh2sh0.039111.20.023825.50.059526.03.39729
7、4.400012.6896302.50005.1754848.888921.2621(元)购买彩票的平均支出:ystWhyh 21.2621h12sh方差估计量:v(yst)Wh(1 fh)11.3104nhh132标准差:se(yst)v(yst)11.3104 3.3631(2)t=1.9610%YV t0.121.2621 1.17681.96 348.139522W sh132hh按比例分配时:n0W sh132hhV348.1395 295.841.1768n0295.84 219.05 220n0295.8411844N所需样本量为n 各层样本量;n1W1n 0.3033220 6
8、6.4431 67n2W2n 0.4976220 109.0083109n3W3n 0.1991220 43.6033 44按尼曼分配时:W1s1 0.303394.4000 2.9470W2s2 0.4976 302.5000 8.6550W3s3 0.1991 848.8889 5.7995W sh13hh 2.9470 8.6550 5.7995 17.401617.40162所需样本量为n 190.541912V(Whsh)/N1.1768348.1395/844各层样本量;n1 nW1s12.9470191 32.2680 32W s17.4016hhW2s28.6550191 94
9、.7672 9517.4016WhshW3s35.7995191 63.5010 64W s17.4016hh(Whsh)2n2 nn3 n4.44.4hWhnh在家人数 nhiphqhWh*ph1234560.180.210.140.090.163030303030302728272628290.90.9333330.90.8666670.9333330.9666670.10.0666670.10.1333330.0666670.0333330.1620.1960.1260.0780.0001019.46E-056.08E-053.23E-050.1493335.49E-050.212667
10、5.38E-050.9240.0003970.22合计(2)当按比例分配时,按尼曼分配时4.54.5依题意,可算得样本量n=200,并有如下表数据17.29823.64313.97444.256511.44669.164714.1185.09693.168103.64Total75.79275.792Whyh2Whsh904.05355.944739.65526.901325.85918.842132.48522.24170.37295.7511892.0711892.07故可得平均支出的分层估计:y Whyh75.79其方差估计:v(y)111892.072W s 59.46hhn200标准
11、差:se(y)v(y)59.4604 7.7195%的置信区间为:(75.791.967.71)(60.68,90.91)。4.64.6W1 0.2,W2 0.3,W3 0.5P1 0.1,P2 0.2,P3 0.4P WhPh0.28样本量为 100 的简单随机抽样估计方差:1 f21N1V S PQ PQ 0.002016nn N 1n按比例分配分层抽样的样本量为:n0W P QhhhV0.0180.0480.120.186 92.260.0020160.002016n n0 934.64.6 另解另解已知 W1=0.2,W2=0.3,W3=0.5,P1=0.1,P2=0.2,P3=0.4
12、P=hWhPh=0.28,Q=1P=0.72 n=100 的简单随机抽样估计方差:V(Psrs)(1f)/100PQ 0.28*0.72/100 =0.002016按比例分配的分层抽样的估计方差:V(Pprop)hWh(1fh)/nh Ph Qh n-1hWh Ph Qh =n-10.2*0.1*0.9+0.3*0.2*0.8+0.5*0.4*0.6 =0.186 n-1故n 92.26 934.84.8(1)由题设,n 100n1 3所以,对于差错率的简单估计:p q 1 p 0.972n13 0.03n100pq 0.030.97 0.0291因而上述估计的标准差:se(p)(1 f)pq
13、n1pq0.0291 0.0171n11001(2)由题设取层权,WA0.7,WB0.3每层的差错率估计分别为:pAn1An12 0.02326,pB1B 0.03509nA43nB57差错率的事后分层估计:ppstWApAWBpB 0.02682sAnApAqA 0.02326nA12sBnBpBqB 0.03446nB1方差:v(ppst)1 f12222(WAsAWBsB)2(1WA)sA(1WB)sB 0.000269nn标准误:se(ppst)v(ppst)0.000269 0.0164第五章第五章5.15.1 记总产量为Y,总播种面积为XX=77 000N=200n=101 f11
14、0/200 0.095n10y yi142.2x xi 2706y 14.22x 270.6yi 2307.2222syxi8183282xiyi 43330.611222(yiny2)31.6818sx(xi nx2)9564.93n 1n11sxy(yixinyx)539.0311n1y142.2 0.05255故有Rx2706 RX 0.0525577000 4046.34总产量的比率估计:YR其方差:2x)2N2(1 f)(y RN(1 f)ii2)2s2 2Rs)5484.173v(Y(sy RRxyxnn 1n Ny 20014.22 2844总产量的简单估计:Ysrs22(y y
15、)N(1 f)N2(1 f)2iv(Ysrs)sy120390.8nn1n比率估计的方差较小,因此效果较好。5.35.3当CXCy时,用第一种方法,即用进行估计;当X时,用第二种方法,2CY2CYX即用Cy进行估计;当X时,两种方法都可使用。2CYxVy1 f21 f22 yVSYCYYnnX1 f21 f22SYR CY 2nnX y)1 fR2(C2C22C C)V V(RYXYXnx当CX y时,V2CYX y 1 f2R CX(2CYCX)0 nx当CX y y 1 f2R CX(2CYCX)0时,V Xxn2CYCX y时,V2CYX当5.45.4 y 1 f2R CX(2CYCX)
16、0 nx)V(y)S2 R2S22RS SCXV(YRRYXYX12CSYV(Y)V(y)YsrsCX 2CY2由题设,cx/cy1.054/1.063 0.9915)cXv(YR1c)v(YYsrscX2 2r1 0.9915 20.6960.9915 0.6029cY2所以与简单估计量比,比率估计量的精度提高了 1-0.6029=39.71%.5.65.6记总产量为Y,总播种面积为XX=460N=140n=10y yi126001 f110/1400.09286n10y 1260 x 2.97x xi 29.7221.3468sxy 499.111sy194911.111sx易得总产量的简
17、单估计:N y 140 112 176400(斤)Ysrsvy1 f2sy0.09286194911.11118098.89n)N vy140 18098.89 140134.532118834.5se(Ysrs比率估计y12600 424.2424Rx29.7 RX yX 12600460 195151.5(斤)YRx29.72N(1 f)222)s)25149053.77v(Y(sy R sx 2RRyxn)v Y5014.88se(YRR回归估计 b syx2sx499.111 370.601.3468ylr y b(x X)1260 370.60(2.97 460/140)1377.004 Ny 1401377.004192780.5(斤)Ylrlr(1 f)nv(ylr)(yi y)b(xi x)21038.614n(n 2)i1(1 f)nse(ylr)v(ylr)(yi y)b(xi x)2 1038.614 32.2275n(n2)i1对比三种估计方法,回归估计具有最高的精度。)Nse(y)14032.2275 4511.86se(Ylrlr
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