《商务统计学2015期中考试卷.docx》由会员分享，可在线阅读，更多相关《商务统计学2015期中考试卷.docx（8页珍藏版）》请在三一文库上搜索。
1、.商务统计期中考试试题Part I: 单选题 (每题 2 分，共 60 分 )1. The universe or totality of items or things under consideration is calleda) a sample.b) a population.c) a parameter.d) a statistic.2. Which of the following is most likely a population as opposed to a sample?a) respondents to a newspaper survey.b) the first
2、5 students completing an assignment.c) every third person to arrive at the bank.d) registered voters in a county.3. A study is under way in Yosemite National Forest to determine the adult height of American pine trees. Specifically, the study is attempting to determine what factors aid a tree in rea
3、ching heights greater than 60 feet tall. It is estimated that the forest contains 25,000 adultAmerican pines. The study involves collecting heights from 250 randomly selected adult American pine trees and analyzing the results. Identify the variable of interest in the study.a) The age of an American
4、 pine tree in Yosemite National Forest.b) The height of an American pine tree in Yosemite National Forest.c) The number of American pine trees in Yosemite National Forest.d) The species of trees in Yosemite National Forest.4. The British Airways Internet site provides a questionnaire instrument that
5、 can be answeredelectronically. Which of the 4 methods of data collection is involved when people complete the questionnaire?a) Published sourcesb) Experimentationc) Surveyingd) Observation5. To monitor campus security, the campus police office is taking a survey of the number of students in a parki
6、ng lot each 30 minutes of a 24-hour period with the goal of determiningwhen patrols of the lot would serve the most students. IfX is the number of students in the lot each period of time, then X is an example ofa) a categorical random variable.b) a discrete random variable.c) a continuous random var
7、iable.d) a statistic.6. An insurance company evaluates many numerical variables about a person before deciding on an appropriate rate for automobile insurance. A representative from a local insurance agency selected a random sample of insured drivers and recorded,X, the number of claims each made in
8、 the last 3 years, with the following results.Xfrequency1 142 183 124 55 1Referring to the table, how many total claims are represented in the sample?a) 15b) 50c) 111d) 250(For Q7 and Q8) A survey was conducted to determine how people rated the quality of programming available on television. Respond
9、ents were asked to rate the overall quality from 0 (no quality at all) to 100 (extremely good quality). The stem-and-leaf display of the data is shown below.StemLeaves3 244 034789995 01123456 125667 0189 27. Referring to the table, what percentage of the respondents rated overall television quality
10、with a rating of 80 or above?a) 0b) 4c) 96d) 1008. Referring to the table, what percentage of the respondents rated overall television quality with a rating between 50 and 75?a) 11b) 40c) 44d) 56.(For Q9 and Q10) The following are the durations in minutes of a sample of long-distance phone calls mad
11、e reported by one long-distance carrier.Time (in Minutes)Relative Frequency0 but less than 50.375 but less than 100.2210 but less than 150.1515 but less than 200.1020 but less than 250.0725 but less than 300.0730more0.029. Referring to the table, if 1,000 calls were randomly sampled, how many calls
12、lasted under 10 minutes?a) 220b) 370c) 410d) 59010. Referring to the table, if 100 calls were randomly sampled, how many calls lasted 15 minutes or longer?a) 10b) 14c) 26d) 7411. You have collected data on the approximate retail price (in $) and the energy cost per year (in $) of 15 refrigerators. W
13、hich of the following is the best for presenting the data?a) A pie chart.b) A scatter diagram.c) A Pareto diagram.d) A contingency table.(For Q12 and Q13) The histogram below represents scores achieved by 200 job applicants on a personality profile.0.300.200.100.00.Rel.Freq.0.200.200.200.100.100.100
14、.1001020304050607012. Referring to the histogram, _ percent of the job applicants scored between 10 and 20.a) 10%b) 20%c) 30%d) 40%13. Referring to the histogram, the number of job applicants who scored between 30 and below 60 is _.a) 20b) 40c) 60d) 8014. Which measure of central tendency can be use
15、d for both numerical and categorical variables?a) Arithmetic mean.b) Median.c) Mode.d) Standard deviation.15. Which of the following statements about the median is not true?a) It is more affected by extreme values than the arithmetic mean.b) It is a measure of central tendency.c) It is equal to Q2.d
16、) It is equal to the mode in bell-shaped normal distributions.16. When extreme values are present in a set of data, which of the following descriptive summary measures are most appropriate:a) CV and range.b) arithmetic mean and standard deviation.c) interquartile range and median.d) variance and int
17、erquartile range.17. A probability distribution is an equation that.a) associates a particular probability of occurrence with each outcome in the sample space.b) measures outcomes and assigns values Xof to the simple events.c) assigns a value to the variability in the sample space.d) assigns a value
18、 to the center of the sample space.18. In a binomial distributiona) the random variable X is continuous.b) the probability of event of interestis stable from trial to trial.c) the number of trials n must be at least 30.d) the results of one trial are dependent on the results of the other trials.19.
19、A lab orders 100 rats a week for each of the 52 weeks in the year for experiments that the lab conducts. Prices for 100 rats follow the following distribution:Price:$10.00$12.50$15.00Probability:0.350.400.25How much should the lab budget for next year s rat orders be, assuming this distributiondoes
20、not change?a) $520b) $637c) $650d) $78020. A multiple-choice test has 30 questions. There are 4 choices for each question. A student who has not studied for the test decides to answer all questions randomly.What type of probability distribution can be used to figure out his chance of getting at leas
21、t 20 questions right?a) binomial distribution.b) Poisson distribution.c) normal distribution.d) none of the above.21. In its standardized form, the normal distributiona) has a mean of 0 and a standard deviation of 1.b) has a mean of 1 and a variance of 0.c) has an area equal to 0.5.d) cannot be used
22、 to approximate discrete probability distributions.22. For some positive value of Z, the probability that a standard normal variable is between 0 and Z is 0.3340. The value ofZ isa) 0.07b) 0.37c) 0.97d) 1.0623. The owner of a fish market determined that the average weight for a catfish is 3.2 pounds
23、 with a standard deviation of 0.8 pound. A citation catfish should be one of the top 2% in weight. Assuming the weights of catfish are normally distributed, at what weight (in pounds) should the citation designation be established?a) 1.56 poundsb) 4.44 poundsc) 4.84 poundsd) 5.20 pounds24. If a part
24、icular batch of data is approximately normally distributed, we would find that approximatelya) 2 of every 3 observations would fall betweenb) 4 of every 5 observations would fall betweenc) 19 of every 20 observations would fall betweend) All the above.1 standard deviation around the mean.1.28 standa
25、rd deviations around the mean.2 standard deviations around the mean.25. Which of the following about the binomial distribution is not a true statement?a) The probability of event of interest must be constant from trial to trial.b) Each outcome is independent of the other.c) The random variable of in
26、terest is continuous.d) Each outcome may be classified as either event of interest or not event of interest.26. Why is the Central Limit Theorem so important to the study of sampling distributions?a) It allows us to disregard the size of the sample selected when the population is not normal.b) It al
27、lows us to disregard the shape of the sampling distribution when the size of the population is large.c) It allows us to disregard the size of the population we are sampling from.d) It allows us to disregard the shape of the population when is large.27. Suppose a sample ofn = 50 items is drawn from a
28、 population of manufactured products andthe weight, X, of each item is recorded. Prior experience has shown that the weight has aprobability distribution with = 6 ounces and = 2.5 ounces. Which of the following is true about the sampling distribution of the sample mean if a sample of size 15 is sele
29、cted?a) The mean of the sampling distribution is 6 ounces.b) The standard deviation of the sampling distribution is 2.5 ounces.c) The shape of the sample distribution is approximately normal.d) All of the above are correct.28. For some positive value of X, the probability that a standard normal vari
30、able is between 0 and + 2X is 0.1255. The value of X isa) 0.99b) 0.40c) 0.32d) 0.1629. A campus program evenly enrolls undergraduate and graduate students. If a random sample of 4 students is selected from the program to be interviewed about the introduction of a new fast food outlet on the ground f
31、loor of the campus building, what is the probability that all 4 students selected are undergraduate students?a) 0.0256b) 0.0625c) 0.16d) 1.0030. If two events are collectively exhaustive, what is the probability that both occur at the same time?a) 0.b) 0.50.c) 1.00.d) Cannot be determined from the i
32、nformation given.Part II: 计算题 :Q1. 某证券公司为了分析上市公司股票价格与公司净资产收益率的关系，收集了各个上市公司的财务数据。现有5 个家电公司上年的净资产收益率和本年平均股票价格数据如下：公司净资产收益率（）本年平均股票价格（元）A3.96.2B1.25.3C1.45.6D6.48.0E4.16.8根据表中给出的数据， 计算这些家电公司净资产收益率和公司平均股票价格之间的协方差（10 分）。.Q2. 一家商业银行为了改进中午 12 点到 13 点间的客户服务水平，提出了一套改进的服务流程。下表是在一个星期的 12 点到 13 点中随机采样的 30 个客户的等
33、待时间（分钟）：X i :0.40.50.50.62.32.42.933.13.23.53.63.83.94.14.24.44.54.74.855.15.15.25.65.76.16.16.26.2i Xi= 116.7,i (X i -) 2 = 88.627a. 计算均值、中位数和众数。 (3 分)b.计算标准差、全距、变异系数、最大样本和最小样本的Z 值。 (5 分 )c. 用五值概括法描述等待时间 (5 分)d. 等待时间中有异常值吗 ?为什么？ (2 分)Q3. 多曼批发商公司的董事长认为公司30%的订单来自新的或第一次合作的客户，该公司用100 个订单的简单随机样本来估计新的或第一次合作的客户所占的比例。a. 该研究中的 的抽样分布是什么？为什么？ (5 分)b.样本比例落在总统比例p=0.30 的范围之内的概率是多少？(5 分)c.当样本容量为 500 时，回答问题 (b)。(5 分).