A.median；meanB.data point；meanC.quartile；medianD.data p……

单项选择题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（）

A.approximation theorem
B.normal probability theorem
C.central limit theorem
D.central normality theorem

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

问答题在显著性水平α＝0.05时能否认为方案A和方案B在药品中转时间上存在差异？

问答题试求总体均值的置信水平为95%的置信区间。

问答题试求药品中转时间差异均值的点估计。

问答题解释回归系数的实际意义。

问答题当广告费用为10000时，销售量为多少？

问答题销售量与广告费用之间的相关系数是多少？