dsc final

The monthly starting salaries of students who receive an MBA degree have a standard deviation of $110. What size sample should be selected to obtain a 0.95 probability of estimating the mean monthly income within $20 or less?

117

The manager of a department store wants to determine what proportion of people who enter the store use the store's credit card for their purchases. What size sample should she take so that at 99% confidence the error will not be more than 8%?

260

.A numerical measure, such as a mean, computed from a population is known as a a. population parameter b. sample parameter c. sample statistic d. sample mean

A

.When the results of experimentation or historical data are used to assign probability values, the method used to assign probabilities is referred to as the a. relative frequency method b. subjective method c. classical method d. posterior method

A

A bank manager wishes to estimate the average waiting time for customers in line for tellers. A random sample of 50 times is measured and the average waiting time is 5.7 minutes. The population standard deviation of waiting time is 2 minutes. Which Excel function could be used to help construct a confidence interval estimate with confidence coefficient of 0.95? A. NORM.INV B. ABS.INT C. INTERVAL D. CONF.T

A

A method of assigning probabilities based upon judgment or belief is referred to as the A. subjective method B. classical method C. empirical method D. revisionist method

A

A normal probability distribution a. is a continuous probability distribution b. is a discrete probability distribution c. can be either continuous or discrete d. always has a standard deviation of 1

A

A numerical description of the outcome of an experiment is called a A. random variable B. variance C. probability function D. descriptive statistic

A

Events A and B are mutually exclusive. Which one of the following statements is also true? A. P(A B) = P(A) + P(B) B. P(A B) = P(A)P(B) C. P(A B) = P(A) + P(B) D. A and B are also independent.

A

If several frequency distributions are constructed from the same quantitative data set, the distribution with the widest class widths will have the A. fewest classes B. most classes C. fewest frequencies D. most frequencies

A

If the sample size n is increased, the A. standard error of the mean decreases B. sample mean increases C. sample standard deviation decreases D. standard error of the mean increases

A

If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect the A. width of the confidence interval to increase B. sample size to increase C. width of the confidence interval to decrease D. width of the confidence interval to remain the same

A

In a data set, the number of observations will always be the same as the number of A. elements B. variables C. data D. data sets

A

In general as the sample size increases, the margin of error A. decreases B. increases C. may either increase or decrease D. stays the same

A

The 50th percentile is same as the A. median B. mode C. third quartile D. mean

A

The measure of location that is the most likely to be influenced by any outliers in a distribution is the A. mean B. range C. median D. mode

A

The purpose of statistical inference is to provide information about the A. population based upon information contained in the sample B. sample based upon information contained in the population C. mean of the sample based upon the mean of the population D. population based upon information contained in the population

A

The standard deviation of all possible values from all possible samples of a given size n drawn from a population is called the A. standard error of the mean B. standardized mean C. fpc D. mean deviation

A

The weight of an object, measured in grams, is an example of a. a continuous random variable b. a discrete random variable c. either a continuous or a discrete random variable, depending on the weight of the object d. either a continuous or a discrete random variable depending on the units of measurement

A

When using Excel's BINOM.DIST function, one should choose the argument TRUE if A. a cumulative probability is desired B. the probability of a success or failure is desired C. the expected value is desired D. a probability is desired

A

A 95% confidence interval for a population mean is determined to be 100 to 120. If the confidence coefficient is reduced to 0.90, the interval for u a. becomes narrower b. becomes wider c. does not change d. becomes 0.1

A becomes narrower

The ability of an interval estimate to contain the value of the population parameter is described by the a. confidence level b. degrees of freedom c. precise value of the population mean u d. None of the other answers are correct.

A confidence level

A theorem that allows us to use the normal probability distribution to approximate the sampling distribution of sample means and sample proportions when the sample size is large enough is the A. approximation theorem B. central limit theorem C. normal probability theorem D. simple random sampling theorem

B

A weighted average of the value of a random variable, where the probability function provides weights is known as A. the variance B. the expected value C. a probability function D. a random variable

B

During a cold winter, the temperature stayed below zero degrees Fahrenheit for ten days (ranging from -20 to -5). The variance of the temperatures for the ten day period A. cannot be computed from all-negative numbers B. must be greater than zero C. is zero since all the numbers are negative D. is negative since all the numbers are negative

B

Given that a population size N is larger than a sample size n, a sample mean A. can never be larger in value than the mean u of the population from which the sample was taken B. can be equal, smaller, or greater in value compared to the mean u of the population from which the sample was taken C. must always be smaller in value than the mean u of the population from which the sample was taken D. can never be equal in value to the mean u of the population from which the sample was taken

B

The sampling error is the a. same as the standard error b. absolute value of the difference between an unbiased point estimate and the corresponding population parameter c. error caused by selecting a bad sample d. standard deviation multiplied by the sample size

B

The sum of relative frequencies for all classes in a relative frequency distribution will always equal A. the number of classes B. 1 C. the number of elements in a data set D. a value between 0 and 1

B

The symbol as in P(A U B) represents A. sample space B. union of events C. universe of events D. intersection of events

B

The symbol as in P(A n B) represents A. sum of the probabilities of events B. intersection of events C. union of events D. complement of events

B

The union of the two events A U B is the event containing A. all the sample points belonging to A or B B. all the sample points belonging to A or B or both C. all the sample points belonging to A or B, but not both D. all the sample points common to both A and B

B

Using a= 0.04, a confidence interval for a population proportion is determined to be 0.65 to 0.75. If the level of significance is decreased, the interval for the population proportion A. becomes narrower B. becomes wider C. does not change D. Not enough information is provided to answer this question.

B

When the data are labels or names used to identify an attribute of the elements, the variable has which scale of measurement? A. interval B. nominal C. ordinal D. ratio

B

Which scale(s) of measurement can be either numeric or nonnumeric? A. interval and ratio B. nominal and ordinal C. nominal D. ordinal

B

.As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution a. becomes larger b. becomes smaller c. stays the same d. None of the other answers are correct

B becomes smaller

.As the sample size increases, the margin of error a. increases b. decreases c. stays the same d. None of the other answers are correct.

B decreases

If the computed mean of a normally distributed set of data is negative, A. the standard deviation is negative B. the variance must also be negative C. a mistake has been made; the mean of a normal distribution cannot be negative D. none of the other answers is correct.

D

If two different distributions have the same mean value, then their A. standard deviations must also be equal B. medians must also be equal C. modes must also be equal D. none of the above

D

In a given distribution, it is possible that the value of the standard deviation could be A. larger than the variance B. zero, and equal to the variance C. one, and equal to the variance D. any one of the above

D

Larger values of the standard deviation result in a normal curve that is a. shifted to the right b. shifted to the left c. narrower and more peaked d. wider and flatter

D

The ability of an interval estimate to contain the value of the population parameter is described by the A. precise value of the population mean B. precise value of the sampling error C. precise value of the sample standard deviation D. confidence level

D

The mean of a sample is a. always equal to the mean of the population b. always smaller than the mean of the population c. computed by summing the data values and dividing the sum by (n - 1) d. computed by summing all the data values and dividing the sum by the number of items

D

The probability of the occurrence of independent event A in an experiment is 1/3. If the experiment is performed 2 times and event A did not occur, then on the third trial event A A. has a 2/3 probability of occurring B. must occur C. will not occur D. may occur

D

Using an = 0.05 a confidence interval for a population mean is determined to be 100 to 120. If is increased to 0.10, the interval for A. does not change B. becomes wider C. becomes 0.1 D. becomes narrower

D

When dealing with the number of occurrences of an event over a specified interval of time, space, distance or volume and when the occurrence or nonoccurrence in any interval is independent of the occurrence or nonoccurrence in any other interval, the appropriate probability distribution is a A. normal distribution B. binomial distribution C. hypergeometric probability distribution D. Poisson distribution

D

Which one of the following is not a measure of location? A. mean B. mode C. median D. variance

D

.An interval estimate is used to estimate a. the shape of the population's distribution b. the sampling distribution c. a sample statistic d. a population parameter

D population parameter

.We can use the normal distribution to make confidence interval estimates for the population proportion, p, when a. np _> 5 b. n(1 - p) _> 5 c. p has a normal distribution d. Both np _> 5 and n(1 - p) _>5

D Both np _> 5 and n(1 - p) _>5

.From a population that is normally distributed with an unknown standard deviation, a sample of 25 elements is selected. For the interval estimation of u, the proper distribution to use is the a. standard normal distribution b. z distribution c. t distribution with 26 degrees of freedom d. t distribution with 24 degrees of freedom

D t distribution with 24 degrees of freedom

When the data are labels or names used to identify an attribute of the elements, the variable has which scale of measurement? a. nominal b. ordinal c. interval d. ratio

A nominal

.For the interval estimation of u when o is assumed known, the proper distribution to use is the a. standard normal distribution b. t distribution with n degrees of freedom c. t distribution with n -1 degrees of freedom d. t distribution with n - 2 degrees of freedom

A standard normal distribution

.In general, higher confidence levels provide a. wider confidence intervals b. narrower confidence intervals c. a smaller standard error d. unbiased estimates

A wider confidence intervals

.In order to estimate the average electric usage per month, a sample of 196 houses was selected and the electric usage determined. a. Assume a population standard deviation of 350 kilowatt hours. Determine the standard error of the mean. b. With a 0.95 probability, determine the margin of error. c. If the sample mean is 2,000 KWH, what is the 95% confidence interval estimate of the population mean?

A: 25 B: 49 C: 1951 to 2049

.The weight of an object, measured to the nearest gram, is an example of a. a continuous random variable b. a discrete random variable c. either a continuous or a discrete random variable, depending on the weight of the object d. either a continuous or a discrete random variable depending on the units of measurement

B

A continuous random variable may assume A. only integer values in an interval or collection of intervals B. any value in an interval or collection of intervals C. only the positive integer values in an interval D. only fractional values in an interval or collection of intervals

B

A graphical method of representing multi-step probability outcomes is A. a histogram B. a probability tree C. an ogive D. a frequency polygon

B

A quantitative measure computed from a sample, such as sample mean, is known as a A. population parameter B. sample statistic C. population statistic D. sample parameter

B

Categorical data a. are always nonnumeric b. may be either numeric or nonnumeric c. are always numeric d. indicate either how much or how many

B may be either numeric or nonnumeric

.In developing an interval estimate of the population mean, if the population standard deviation is unknown a. it is impossible to develop an interval estimate b. a sample proportion can be used c. the sample standard deviation and t distribution can be used d. None of the other answers are correct.

C the sample standard deviation and t distribution can be used

A numerical measure of linear association between two variables is the A. coefficient of variation B. variance C. coefficient of correlation D. standard deviation

C

A simple random sample of 28 observations was taken from a large population. The sample mean equaled 50. Fifty is A. a sample parameter B. a population parameter C. a point estimate D. the mean of the sampling distribution

C

A standard normal distribution is a normal distribution with A. any mean and any standard deviation B. any mean and a standard deviation of 1 C. a mean of 0 and a standard deviation of 1 D. a mean of 1 and a standard deviation of 0

C

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. the expected value d. None of the answers is correct

C

An interval estimate is used to estimate A. the range of the population distribution B. the sampling distribution C. a population parameter D. a sample statistic

C

Data collected at the same, or approximately the same, point in time are A. static data B. time series data C. cross-sectional data D. one-dimensional data

C

For a population with an unknown distribution, the form of the sampling distribution of sample means is A. approximately normal only if > 0.05 B. approximately normal only if < 0.05 C. approximately normal for large sample sizes, generally as long as n 30 D. approximately normal for all sample sizes

C

For a standard normal distribution, the probability of z 0 is A. zero B. -0.5 C. 0.5 D. one

C

If sampling from a normally distributed population, the sampling distribution of is normal for A. large sample sizes B. small sample sizes C. any sample size D. sample sizes greater than 30

C

In general, higher confidence levels provide A. unbiased estimates B. a smaller standard error C. wider confidence intervals D. narrower confidence intervals

C

Quantitative data A. are always labels B. are always nonnumeric C. are always numeric D. may be either numeric or nonnumeric

C

Sampling error is A. bias caused by selecting a bad sample B. not taking a large enough sample C. difference between point estimate and population parameter D. not taking enough samples

C

The addition rule applies when we are interested in computing the probability of A. independent events B. the intersection of events C. the union of events D. conditional events

C

The probability distribution of all possible values of the sample mean, from all possible samples of a given size drawn from a population, is called the A. standard error B. random variation C. sampling distribution of the sample mean D. central probability distribution

C

Which of the following is a characteristic of a binomial experiment? A. at least 2 outcomes are possible on each trial B. the probability of success changes from trial to trial C. the trials are independent D. all of these answers are correct.

C

Which of the following is/are a measure of variability? A. percentile B. quartile C. interquartile range D. all of the above

C

A manufacturer wants to estimate the proportion of defective items that are produced by a certain machine. A random sample of 50 items is taken. Which Excel function would not be appropriate to construct a confidence interval estimate? a. NORMSINV b. COUNTIF c. STDEV d. All are appropriate

C STDEV

Quantitative data a. are always nonnumeric b. may be either numeric or nonnumeric c. are always numeric d. are always labels

C are always numeric

.The probability assigned to each experimental outcome must be a. any value larger than zero b. smaller than zero c. one d. between zero and one

D

.Statistical inference a. refers to the process of drawing inferences about the sample based on the characteristics of the population b. is the same as descriptive statistics c. is the process of drawing inferences about the population based on the information taken from the sample d. is the same as a census

C is the process of drawing inferences about the population based on the information taken from the sample

A common graphical presentation of quantitative data is a A. relative frequency distribution B. bar chart C. pie chart D. histogram

D

A random variable that can assume only a finite number of values is referred to as a(n) A. normal random variable B. probability density function C. discrete probability function D. discrete random variable

D

A tabular method that can be used to summarize the data on two variables simultaneously is called a A. histogram B. simultaneous trendline C. dot plot D. crosstabulation

D

An estimate of a population parameter that provides an interval believed to contain the value of the parameter is known as the A. population estimate B. parameter value C. confidence level D. interval estimate

D

Bayes' theorem is used to compute A. prior probabilities B. the union of events C. both prior probabilities and the union of events D. posterior probabilities

D

Categorical data can be graphically represented by using a A. crosstabulation B. histogram C. scatter diagram D. bar chart

D

If P(A) = 0.5 and P(B) = 0.5, then P(A U B) A. equals 0.00 B. equals 0.25 C. equals 1.00 D. cannot be determined from the information given

D

.A graphical device for depicting qualitative data that have been summarized in a frequency distribution, relative frequency distribution, or percent frequency distribution is a(n) a. histogram b. stem-and-leaf display c. ogive d. bar graph

D

.A simple random sample of size n from a finite population of size N is a sample selected such that each possible sample of size a. N has the same probability of being selected b. n has a probability of 0.5 of being selected c. n has a probability of 0.1 of being selected d. n has the same probability of being selected

D

.The measure of location that is the most likely to be influenced by extreme values in the data set is the a. range b. median c. mode d. mean

D