A theorem that allows us to use thenormal probability distribution to approximate the sampling distribution of sample means and sample proportions whenever the sample size is large is known as the（）

单项选择题The purpose of statistical inference is to provide information about the（）

A.sample based upon information contained in the population
B.population based upon information contained in the sample
C.population based upon information contained in the population
D.mean of the sample based upon the mean of the population

单项选择题If A and B are independent events，then（）

A.P（A） must be equal to P（B）
B.P（A） must be greater thanP（B）
C.P（A） must be less than P（B）
D.P（A） must be equal to P（A│B）

单项选择题Exhibit 2 The following represents the probability distribution for the daily demand of computers at a local store. Refer to Exhibit 2.The probability of having a demand for at least two computers is（）

A.0.7
B.0.3
C.0.4
D.1.0

单项选择题The student body of a large university consists of 60%female students.A random sample of 8 students is selected.What is the probability that among the students in the sample exactly two are female？（）

A.0.0896
B.0.2936
C.0.0413
D.0.0007

单项选择题A weighted average of the value of a random variable, where the probability function provides weights is known as（）

A.a probability function
B.a random variable
C.thee xpected value
D.random function

单项选择题A sample of 400 observations will be taken from an infinite population. The population proportion equals 0.8. The probability that the sample proportion will be greater than 0.83 is（）

A.0.4332
B.0.9332
C.0.0668
D.0.5668

单项选择题From a population of 500 elements，a sample of 225 elements is selected.It is known that the variance of the population is 900.The standard error of the mean is approximately（）

A.1.1022
B.2
C.30
D.1.4847

单项选择题Given the following information：Standar ddeviation=8 Coefficient of variation=64% The mean would then be（）

A.12.5
B.8
C.0.64
D.1.25

单项选择题假设检验中拒绝域为（）

A.Z<-1.96
B.Z>1.96
C.Z>1.65
D.Z<-1.65

单项选择题一家电器销售公司的管理人员认为，每月的销售额是广告费用的函数，并想通过广告费用对月销售额作出估计。用电视广告费用作自变量，销售额作因变量进行回归分析。下表给出了相关的分析结果， 下列说法正确的是（）

A.广告费用每增加$1，000， 销售额增加$1.420 211
B.广告费用每增加$1，000， 销售额增加$1420. 211
C.广告费用每增加$1420.211， 销售额增加$1000
D.广告费用每增加$1， 销售额增加$363.689 1