Claudia Taylor, Director of Global Industrial Sales in Melbourne, is concerned by a deteriorating sales trend. Specifically, the number of customers is stable at 1500 but they are purchasing less each year. She orders her staff to search for causes of the downward trend by selecting a focus group of 40 industrial customers. For this study, the set of 40 industrial customers is a （）.

单项选择题Michael Bayley, Marketing Director of UniPower’s Electrical Division, is leading a study to identify and assess the relative importance of product features. Michael directs his staff to design a survey questionnaire for distribution to all of UniPower’s 954 customers. For this study, the set of 954 customers is a （）.

A.statistic
B.population
C.parameter
D.sample

单项选择题Penny Bauer, Chief Financial Officer of Harrison Haulage, suspects irregularities in the payroll system, and orders an inspection of ‘each and every payroll voucher issued since 1 January 2005’. Five per cent of the payroll vouchers contained material errors. This is an example of （）.

A.nonparametric statistics
B.nominal data
C.descriptive statistics
D.inferential statistics

单项选择题X is a discrete random variable that can have values from 0 to infinity, and occurrences of the events X counts are independent. The standard deviation of X is equal to the square root of the mean. The probability distribution of X is a(n) （）distribution.

A.binomial
B.uniform
C.normal
D.Possion

单项选择题The empirical rule tells us that approximately of the values cluster within a distance of 1 standard deviation from the mean for a bell-shaped distribution（）

A.68%
B.95%
C.99.7%
D.none of the above

单项选择题The reason that we prefer the sample standard deviation as our measure of typical variation instead of the sample variance is that（）

A.the variance is not as accurate a measurement as the standard deviation
B.the standard deviation has been corrected for bias while the variance has not
C.the standard deviation is in the same units as the data values.
D.the variance is in the same units as the data values.

单项选择题The sum of the deviations may be 0.00.To get around this problem，we use the（）of the deviations

A.square
B.absolute value
C.minimum
D.maximum

单项选择题deviation is the distance between a（）and the（）.（）

A.median；mean
B.data point；mean
C.quartile；median
D.data point；median

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）