商务统计学-2015期中考试卷

《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 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 Americanpine trees. Specifically, the study is attempting to determine what factors aid a tree inreaching heights greater than 60 feet tall. It is estimated that the forest contains 25,000 adult American pines. The study involves collecting heights from 250 randomly selected adultAmerican pine trees and analyzing the results. Identify the variable of interest in the study.a)The age of an American 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 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 ofstudents in a parking lot each 30 minutes of a 24-hour period with the goal of determiningwhen patrols of the lot would serve the most students. If X 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 variable.d) a statistic.6.An insurance company evaluates many numerical variables about a person before decidingon an appropriate rate for automobile insurance. A representative from a local insuranceagency selected a random sample of insured drivers and recorded, X, the number of claims each made in the last 3 years, with the following results.X frequency1 142 183124 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. Respondents 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.Stem Leaves3 244 034789995 01123456 125667 0189 27.Referring to the table, what percentage of the respondents rated overall television qualitywith a rating of 80 or above?a)0b) 4c)96d)1008.Referring to the table, what percentage of the respondents rated overall television qualitywith 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 made reported by one long-distance carrier.Time (in Minutes) Relative Frequency0 but less than 5 0.375 but less than 10 0.2210 but less than 15 0.1515 but less than 20 0.1020 but less than 25 0.0725 but less than 30 0.0730more 0.029.Referring to the table, if 1,000 calls were randomly sampled, how many calls lasted under10 minutes?a)220b)370c)410d)59010.Referring to the table, if 100 calls were randomly sampled, how many calls lasted 15minutes 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. Which 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.12.Referring to the histogram, ________ percent of the job applicants scored between 10 and20.a)10%b)20%c)30%d)40%13.Referring to the histogram, the number of job applicants who scored between 30 and below60 is _______.a)20b)40c)60d)8014.Which measure of central tendency can be used for both numerical and categoricalvariables?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)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 descriptivesummary measures are most appropriate:a)CV and range.b)arithmetic mean and standard deviation.c)interquartile range and median.d)variance and interquartile range.17.A probability distribution is an equation thata)associates a particular probability of occurrence with each outcome in the samplespace.b)measures outcomes and assigns values of X to the simple events.c)assigns a value to the variability in the sample space.d)assigns a value to the center of the sample space.18.In a binomial distributiona)the random variable X is continuous.b)the probability of event of interest is 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.A lab orders 100 rats a week for each of the 52 weeks in the year for experiments that thelab conducts. Prices for 100 rats follow the following distribution:Price: $10.00 $12.50 $15.00Probability: 0.35 0.40 0.25How much should the lab budget for next year’s rat orders be, assuming this distribution does not change?a)$520b)$637c)$650d)$78020.A multiple-choice test has 30 questions. There are 4 choices for each question. A studentwho 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 least 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 to approximate discrete probability distributions.22.For some positive value of Z, the probability that a standard normal variable is between 0and Z is 0.3340. The value of Z 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 poundswith 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 particular batch of data is approximately normally distributed, we would find thatapproximatelya) 2 of every 3 observations would fall between ±1 standard deviation around the mean.b) 4 of every 5 observations would fall between ±1.28 standard deviations around the mean.c)19 of every 20 observations would fall between ±2 standard deviations around the mean.d)All the above.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 interest is continuous.d)Each outcome may be classified as either "event of interest" or "not event ofinterest."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 notnormal.b)It allows us to disregard the shape of the sampling distribution when the size of thepopulation 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 n is large.27.Suppose a sample of n = 50 items is drawn from a population of manufactured products andthe weight, X, of each item is recorded. Prior experience has shown that the weight has aprobability distribution with μ= 6 ounces and σ= 2.5 ounces. Which of the following is true about the sampling distribution of the sample mean if a sample of size 15 is selected?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 variable is between 0and +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 sampleof 4 students is selected from the program to be interviewed about the introduction of a new fast food outlet on the ground floor 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 sametime?a)0.b)0.50.c) 1.00.d)Cannot be determined from the information 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（10分）。