DSC Final

The monthly number of applications for admission to UD is a discrete random variable. True or False

True

On a December day, the probability of snow is .30. The probability of a "cold" day is .50. The probability of snow and a "cold" day is .15. Thus, snow and "cold" weather are _____. A. discrete events B. mutually exclusive events C. independent events D. dependent events

C. independent events

The binomial probability distribution is most symmetric when _____. A. n equals p B. p approaches 1 C. p equals 0.5 D. n is 30 or greater

C. p equals 0.5

A description of how the probabilities are distributed over the values the random variable can assume is called a(n) _____. A. random variable B. probability function C. probability distribution D. expected value

C. probability distribution

The margin of error in an interval estimate of the population mean is a function of all of the following EXCEPT _____. A. level of significance B. sample size C. sample mean D. variability of the population

C. sample mean

Whenever the population standard deviation is unknown, which distribution is used in developing an interval estimate for a population mean? A. z distribution B. uniform distribution C. t distribution D. binomial distribution

C. t distribution

All of the following are examples of observational studies except: A. an online survey to record your satisfaction with a company's service. B. the number of cars running a stop sign in a residential area during rush hour. C. the behavior of Walmart shoppers after they are given a $20 gift card from the store. D. a Gallup poll measuring the approval rating of the president.

C. the behavior of Walmart shoppers after they are given a $20 gift card from the store.

Highway patrol officers measure the speed of automobiles on a highway using radar equipment. The random variable in this experiment is speed, measured in miles per hour. This random variable is a discrete random variable. true or false

False

The binomial probability distribution is appropriate to use for "without replacement" type problems. true or False

false

The correlation coefficient can never be negative. true or false

false

The exponential distribution is a discrete probability distribution. true or False

false

The mean is a better measure of center than the median if there is an outlier in the data set. true or false

false

The mean of a standard normal random variable is one. true or False

false

A pie chart is appropriate for categorical data. true or false

true

A prediction made from sample data is an example of an inferential statistic. True or false

true

Cluster sampling is a probability-based sampling method. True or false

true

If the random variable X = number of occurrences has a Poisson distribution, then the random variable Y = time between occurrences has an exponential distribution. True or false

true

Taking repeated samples until you obtain the desired result is not an ethically acceptable statistical practice. True or False

true

The Empirical Rule can only be applied if the data distribution is bell-shaped. true or false

true

The level of significance α (alpha) is the probability that the confidence interval does not contain the value of the parameter being estimated. True or false

true

The median is used in creating a boxplot. true or false

true

The sample mean provides a point estimate for the population mean. True or false

true

The symbol for the sample variance is s2. true or false

true

the variable Z represents a standard normal random variable. True or false

true

The RAND() function in Excel can be used to find a probability. true or False

false

If A and B are independent events with P(A) = .2 and P(B) = .6, then P(A ∪ B) = _____. A. .68 B. .12 C. .60 D. .62

A. .68

A proficiency exam was given to employees of a firm. 60% of the firm's employees passed the exam. 30% of the employees are male. The probability that an employee was female and passed the examination was 0.56. What is the probability that a randomly selected employee is female or passed the exam? A. 0.74 B. 0.235 C. 0.34 D. 0.70

A. 0.74

A proficiency exam was given to employees of a firm. Seventy percent of the firm's employees passed the exam. The probability that an employee was female and passed the examination was 0.56. If a randomly selected employee passed the exam, what is the probability that the employee is a female? A. 0.80 B. .392 C. 1.26 D. 0.30

A. 0.80

Test 4 chapter 6 The ages of students at a university are normally distributed with a mean of 21. What percentage of the student body is at least 21 years old? A. 50% B. 21% C. It could be any value, depending on the magnitude of the standard deviation. D. 1.96%

A. 50%

Posterior probabilities are computed using _____ A. Bayes' theorem B. the classical method C. Chebyshev's Theorem D. the Empirical Rule

A. Bayes' theorem

Which of the following is NOT a characteristic of the normal probability distribution? A. The graph of the curve is the shape of a rectangle. B. The total area under the curve is always equal to 1. C. The random variable assumes a value within plus or minus three standard deviations of its mean 99.72% of the time. D. The mean is equal to the median, which is also equal to the mode.

A. The graph of the curve is the shape of a rectangle.

Which of the following is NOT a probability-based sampling method? A. Volunteer Sampling B. Stratified Random Sampling C. Simple Random Sampling D. Cluster Sampling

A. Volunteer Sampling

The weight of items produced by a machine is normally distributed with a mean of 8 ounces and a standard deviation of 2 ounces. What is the random variable in this experiment? A. Weight of items produced by a machine B. 8 ounces C. Accuracy of the machine D. 2 ounces

A. Weight of items produced by a machine

Exponential distributions _____. A. are not skewed B. are skewed to the right C. are skewed to the left D. can be skewed to the left or right

A. are not skewed

A graphical summary of data that is based on a five-number summary is a _____. A. boxplot B. scatter diagram C. stem-and-leaf display D. histogram

A. boxplot

The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the _____. A. degrees of freedom B. finite correction factor C. sample size D. standard deviation

A. degrees of freedom

A continuous probability distribution that is useful in describing the time, or space, between occurrences of an event is a(n) _____ probability distribution. A. exponential B. normal C. Poisson D. uniform

A. exponential

All of the following are true about the standard error of the mean EXCEPT _____. A. it is larger than the standard deviation of the population B. it decreases as the sample size increases C. its value is influenced by the standard deviation of the population D. it measures the variability in sample means

A. it is larger than the standard deviation of the population

The expected value of a random variable is the _____. A. mean value B. median value C. most occurring value D. most probable value

A. mean value

Which of the following is a point estimator? A. s B. t C. σ D. p

A. s

An important numerical measure related to the shape of a distribution is the _____. A. skewness B. relative location C. variance D. correlation coefficient

A. skewness

The standard deviation of all possible x-bar values is called the _____. A. standard error of the mean B. standard error of proportion C. mean deviation D. central variation

A. standard error of the mean

The probability Pete will catch fish when he goes fishing is .8. Pete is going fishing 3 days next week. The random variable in this problem is ________________________________________. A. the number of days out of 3 that Pete catches fish B. the 3 days C. the .8 probability of catching fish D. the number of fish in the body of water

A. the number of days out of 3 that Pete catches fish

he _____ denotes the number of standard deviations xi is from the mean . A. z-score B. variance C. median D. normal deviation

A. z-score

Which of the following symbols represents the standard deviation of a population? A. σ B. σ 2 C. D. μ A proficiency exam was given to employees of a firm. Seventy percent of the firm's employees passed the exam. The probability that an employee was female and passed the examination was 0.56. If a randomly selected employee passed the exam, what is the probability that the employee is a female? A. 0.80 B. .392 C. 1.26 D. 0.30

A. σ

The assembly time for a product is uniformly distributed between 6 and 10 minutes. The probability of assembling the product in less than 6 minutes is _____. A. 1 B. 0 C. .15 D. .50

B. 0

The use of the normal probability distribution as an approximation of the sampling distribution of is based on the condition that both np and n (1 - p) equal or exceed _____. A. .05 B. 5 C. 15 D. 30

B. 5

A set of visual displays that organizes and presents information that is used to monitor the performance of a company or organization in a manner that is easy to read, understand, and interpret is called a: A. data visualization. B. crosstabulation. C. data dashboard. D. scatter diagram.

C. data dashboard.

Which of the following would likely display a negative relationship when creating a scatter diagram? A. The number of miles that a car is driven and the amount of fuel consumed B. The number of classes a student misses during a semester and the grade obtained in the course C. The amount of time a student spends studying and their average test scores D. The amount of rain that falls in the spring and how quickly the grass grows

B. The number of classes a student misses during a semester and the grade obtained in the course

Which of the following is NOT a characteristic of the normal probability distribution? A. The distribution is symmetrical. B. The standard deviation must be 1. C. The mean of the distribution can be negative, zero, or positive. D. The mean, median, and mode are equal.

B. The standard deviation must be 1.

When the population has a normal distribution, the sampling distribution of x-bar is normally distributed _____. A. for any sample size of 30 or more B. for any sample size C. for any sample from a finite population D. for any sample size of 50 or more

B. for any sample size

For a uniform probability density function, the height of the function _____. A. decreases as x increases B. is the same for each value of x C. is different for various values of x D. cannot be larger than 1

B. is the same for each value of x

The key difference between binomial and hypergeometric distributions is that with the hypergeometric distribution the _____. A. probability of success must be less than .5 B. probability of success changes from trial to trial C. trials are independent of each other D. random variable is continuous

B. probability of success changes from trial to trial

If P(A) = .62, P(B) = .56, and P(A ∪ B) = .70, then P(B | A) = _____. A. .4800 B. .9032 C. .7742 D. .6340

C. .7742

The weight of items produced by a machine is normally distributed with a mean of 8 ounces and a standard deviation of 2 ounces. What is the probability that a randomly selected item weighs exactly 8 ounces? A. .3413 B. 1.0 C. 0 D. .5

C. 0

Examples of categorical data include allof the following except: A. extra large. B. blonde. C. 90210 (Beverly Hills). D. 228 lbs.

C. 90210 (Beverly Hills).

Events A and B are mutually exclusive. Which 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

C. P(A ∪ B) = P(A) + P(B)

Excel's __________ can be used to construct a crosstabulation. A. Chart Tools B. SUM function C. Pivot Table tool D. COUNTIF function A company wants to enhance the benefits for its yearly healthcare package offering. It observes the set of employees who smoke on their break times at 10 a.m., 12 p.m., and 2 p.m. It records the number of cigarettes smoked by each individual. This is an example of: A. a randomized study. B. a study using existing sources. C. an observational study. D. a controlled experiment.

C. Pivot Table tool

In the textile industry, a manufacturer is interested in the number of blemishes or flaws occurring in each 100 feet of material. The probability distribution that has the greatest chance of applying to this situation is the _____. A. hypergeometric distribution B. binomial distribution C. Poisson distribution D. uniform distribution

C. Poisson distribution

If one wanted to find the probability of 10 customer arrivals in an hour at a service station, one would generally use the _____. A. discrete uniform distribution B. binomial probability distribution C. Poisson probability distribution D. hypergeometric probability distribution

C. Poisson probability distribution

This sampling method involves breaking the population up into subgroups and taking a simple random sample from each of the subgroups. A. Cluster Sampling B. Systematic Sampling C. Stratified Random Sampling D. Simple Random Sampling

C. Stratified Random Sampling

The interquartile range is used as a measure of variability to overcome what difficulty of the range? A. The range is difficult to compute. B. The range is negative. C. The range is influenced too much by extreme values. D. The sum of the range variances is zero.

C. The range is influenced too much by extreme values.

A company wants to enhance the benefits for its yearly healthcare package offering. It observes the set of employees who smoke on their break times at 10 a.m., 12 p.m., and 2 p.m. It records the number of cigarettes smoked by each individual. This is an example of: A. a randomized study. B. a study using existing sources. C. an observational study. D. a controlled experiment.

C. an observational study.

The summaries of data, which may be tabular, graphical, or numerical, are referred to as: A. categorical statistics. B. quantitative statistics. C. descriptive statistics. D. inferential statistics.

C. descriptive statistics.

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 remain the same B. width of the confidence interval to decrease C. width of the confidence interval to increase D. sample size to increase

C. width of the confidence interval to increase

The number of observations in a complete data set having 20 elements and 3 variables is: A. 20 + 3 or 23. B. 20*3 or 60. C. 20 - 3 or 17. D. 20.

D. 20.

The fact that the sampling distribution of the sample mean can be approximated by a normal probability distribution whenever the sample size is large is based on the _____. A. fact that there are tables of areas for the normal distribution B. normal probability theorem C. assumption that the population has a normal distribution D. Central Limit Theorem

D. Central Limit Theorem

What type of function defines the probability distribution of ANY continuous random variable? A. Uniform distribution function B. Exponential distribution function C. Normal distribution function D. Probability density function

D. Probability density function

Which of the following is NOT a characteristic of an experiment where the binomial probability distribution is applicable? A. Exactly two outcomes are possible on each trial. B. The experiment has a sequence of n identical trials. C. The probabilities of the outcomes do not change from one trial to another. D. The trials are dependent.

D. The trials are dependent.

A probability distribution showing the probability of x successes in n trials, where the probability of success does not change from trial to trial, is termed a _____. A. uniform probability distribution B. hypergeometric probability distribution C. Poisson probability distribution D. binomial probability distribution

D. binomial probability distribution

In a post office, the mailboxes are numbered from 1 to 5,000. These numbers represent A. quantitative data B. either categorical or quantitative data C. time series data D. categorical data

D. categorical data

The coefficient of variation indicates how large the standard deviation is relative to the _____. A. variance B. range C. median D. mean

D. mean

After the data have been arranged from smallest value to largest value, the value in the middle is called the _____. A. mean B. range C. interquartile range D. median

D. median

To compute a binomial probability. we must know all of the following except the _____. A. number of trials B. value of the random variable C. probability of success D. number of elements in the population

D. number of elements in the population

A single numerical value used as an estimate of a population parameter is known as a _____. A. planning value B. parameter C. standard error D. point estimate

D. point estimate

The general form of an interval estimate of a population mean or population proportion is the _____ plus or minus the _____. A. level of significance, degrees of freedom B. population mean, standard error C. planning value, confidence coefficient D. point estimate, margin of error

D. point estimate, margin of error

The Central Limit Theorem can only be used when the population being sampled is normally distributed. true or False

false

The Poisson random variable is an example of a continuous random variable. true or false

false

A histogram is appropriate to be used for categorical data. true or False

false

An interval estimate provides a single value estimate for a population parameter. true or False

false

Every confidence interval constructed will contain the value of the parameter being estimated. true or False

false

In a crosstabulation, both variables must be quantitative. true or False

false

In combinations, the order of selection is important. true or False

false

Numerical calculations are always appropriate for nominal data. true or False

false