题目
A.Judgment sampling
B.Quota sampling
C.Simple random
D.Convenienc
E.Cluster
第1题
有以下程序: #include<iostream> using namespace std; class sample { private: int n; public: sample(){} sample(int m) { n=m; } sample add(sample s1,sample s2) { this->n=s1.n+s2.n; return(*this); }
A.n=10
B.n=5
C.n=20
D.n=15
第2题
We have tested a plant's emissions of particulates and found the following data:
Sample number | Stack velocity, ft/s | Particle concentration, g/m3 |
1 2 3 | 50 60 40 | 0.50 0.30 0.70 |
Each sample represents the average over a 20-min period. What was the average particle concentration in this stack over the whole 60 min of this test?
第3题
有如下程序: #include<iostream> using namespace std; class sample { private: int x,y; public: sample(int i,int j) { x=i; y=j; } void disp() { cout<<"displ"<<endl; } void disp()const { cout<<"disp2"<<endl; } }; int main() { const sample a(1,2); a.disp(); return 0; } 该程序运行后的输出结果是()。
A.disp1
B.disp2
C.disp1 disp2
D.程序编译时出错
第4题
B.They both need a sampling frame of each of the subgroups of the target population.
C.In both of them,researchers want to ensure that all strata are included in the sample in order to enhance the representativeness of the sample and/or to enable comparisons between strA
D.Stratified sampling does not need a sampling frame to generate a stratified sampl
E.
E.In both of them,once the sample number of each subgroup is defined,samples are drawn in simple random sampling or systematic sampling metho
D.
第5题
在考生文件夹下,“sampl。mdb”数据库文件中已建立表对象“tVisitor”,同时在考生文件夹下还存有“exam.mdb”数据库文件。试按以下操作要求,完成表对象“tVisitor”的编辑和表对象“tLine”的导入:
(1)设置“游客ID”字段为主键。
(2)设置“姓名”字段为“必填”字段。
(3)设置“年龄”字段的“有效性规则”属性为:大于等于10且小于等于60。
(4)设置“年龄”字段的“有效性文本”属性为:“输入的年龄应在10岁到60岁之间,请重新输入。”。
(5)在编辑完的表中输入如下一条新记录,其中“照片”字段数据设置为考生文件夹下的“照片1.bmp”图像文件。
(6)将“exam.mdb”数据库文件中的表对象“tLine”导入到“sampl.mdb”数据库文件内,表名不变。
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