IS 242 1

For some positive value of Z, the probability that a standardized normal variable is between 0 and Z is 0.3340. The value of Z is A) 0.97 B) 0.37 C) 0.07 D) 1.06

A

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 reaching 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 adult American pine trees and analyzing the results. Identify the sample in the study. A) the 25,000 adult American pine trees in the forest B) all the adult American pine trees taller than 60 feet C) all American pine trees, of any age, in the forest D) the 250 randomly selected adult American pine trees

D

In a perfectly symmetrical bell-shaped "normal" distribution A) the arithmetic mean equals the median. B) the arithmetic mean equals the mode. C) the median equals the mode. D) all of the above

D

The estimation of the population average family expenditure on food based on the sample average expenditure of 1,000 families is an example of A) a statistic. B) descriptive statistics. C) a parameter. D) inferential statistics.

D

A probability distribution is an equation that A) associates a particular probability of occurrence with each outcome in the sample space. B) assigns a value to the center of the sample space. C) measures outcomes and assigns values of X to the simple events. D) assigns a value to the variability in the sample space.

A

According to a survey of American households, the probability that the residents own 2 cars if annual household income is over $25,000 is 80%. Of the households surveyed, 60% had incomes over $25,000 and 70% had 2 cars. The probability that the residents of a household own 2 cars and have an income over $25,000 a year is: A) 0.48 B) 0.12 C) 0.18 D) 0.22

A

True or False: The answer to the question "How many hours on average do you spend watching TV every week?" is an example of a ratio scaled variable.

A

Which measure of central tendency can be used for both numerical and categorical variables? A) mode B) median C) arithmetic mean D) geometric mean

A

According to a survey of American households, the probability that the residents own 2 cars if annual household income is over $25,000 is 80%. Of the households surveyed, 60% had incomes over $25,000 and 70% had 2 cars. The probability that annual household income is over $25,000 if the residents of a household own 2 cars is: A) 0.48 B) 0.50 C) 0.69 D) 0.42

C

For some positive value of Z, the probability that a standardized normal variable is between 0 and Z is 0.3770. The value of Z is A) 0.81 B) 0.18 C) 1.16 D) 1.47

C

A summary measure that is computed to describes a characteristic of an entire population is called A) the scientific method. B) a parameter. C) a statistic. D) a census.

B

According to the Chebyshev rule, at least 75% of all observations in any data set are contained within a distance of how many standard deviations around the mean? A) 1 B) 2 C) 3 D) 4

B

According to the empirical rule, if the data form a "bell-shaped" normal distribution, __________ percent of the observations will be contained within 2 standard deviations around the arithmetic mean. A) 88.89 B) 95.44 C) 68.26 D) 93.75

B

The chancellor of a major university was concerned about alcohol abuse on her campus and wanted to find out the portion of students at her university who visited campus bars on the weekend before the final exam week. Her advisor took a random sample of 250 students. The portion of students in the sample who visited campus bars on the weekend before the final exam week is an example of A) a discrete random variable. B) a statistic. C) a parameter. D) a categorical random variable.

B

The process of using sample statistics to draw conclusions about true population parameters is called A) descriptive statistics. B) statistical inference. C) the scientific method. D) sampling.

B

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 information given.

D

If two events are independent, what is the probability that they both occur? A) 0 B) 0.50 C) 1.00 D) Cannot be determined from the information given.

D

If we know that the length of time it takes a college student to find a parking spot in the library parking lot follows a normal distribution with a mean of 3.5 minutes and a standard deviation of 1 minute, find the probability that a randomly selected college student will take between 2 and 4.5 minutes to find a parking spot in the library parking lot. A) 0.4938 B) 0.2255 C) 0.0919 D) 0.7745

D

Jared was working on a project to look at global warming and accessed an Internet site where he captured average global surface temperatures from 1866. Which of the four methods of data collection was he using? A) surveying B) observation C) experimentation D) published sources

D

The British Airways Internet site provides a questionnaire that can be answered electronically. Which of the 4 methods of data collection is involved when people complete the questionnaire? A) published sources B) observation C) experimentation D) surveying

D

In its standardized form, the normal distribution A) has an area equal to 0.5. B) has a mean of 1 and a variance of 0. C) has a mean of 0 and a standard deviation of 1. D) cannot be used to approximate discrete probability distributions.

C

When using the general multiplication rule, P(A and B) is equal to A) P(A)P(B). B) P(A\B)P(B). C) P(A)/P(B). D) P(B)/P(A).

B

A telemarketer set the company's computerized dialing system to contact every 25th person listed in the local telephone directory. What sampling method was used? A) simple random sample B) cluster sample C) systematic sample D) stratified sample

C

Given that X is a normally distributed random variable with a mean of 50 and a standard deviation of 2, find the probability that X is between 47 and 54

.9104

If two events are mutually exclusive, 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 information given.

A

The probability that house sales will increase in the next 6 months is estimated to be 0.25. The probability that the interest rates on housing loans will go up in the same period is estimated to be 0.74. The probability that house sales or interest rates will go up during the next 6 months is estimated to be 0.89. The probability that both house sales and interest rates will increase during the next 6 months is: A) 0.10 B) 0.705 C) 0.185 D) 0.90

A

The chancellor of a major university was concerned about alcohol abuse on her campus and wanted to find out the portion of students at her university who visited campus bars on the weekend before the final exam week. Her advisor took a random sample of 250 students. The total number of students in the sample who visited campus bars on the weekend before the final exam week is an example of A) a continuous random variable. B) a discrete random variable. C) a categorical random variable. D) a parameter.

B

The universe or "totality of items or things" under consideration is called A) a sample. B) a population. C) a statistic. D) a parameter.

B

Those methods involving the collection, presentation, and characterization of a set of data in order to properly describe the various features of that set of data are called A) sampling. B) descriptive statistics. C) the scientific method. D) statistical inference.

B

True or False: The answer to the question "What is your favorite color?" is an example of an ordinal scaled variable.

B

The connotation "expected value" or "expected gain" from playing roulette at a casino means A) the amount you expect to "gain" on a single play. B) the amount you need to "break even" over many plays. C) the amount you expect to "gain" in the long run over many trials. D) the amount you should expect to gain if you are lucky.

C

Which of the following is NOT a reason for the need for sampling? A) It is usually too costly to study the whole population. B) It is sometimes destructive to observe the entire population. C) It is always more informative to investigate a sample than the entire population. D) It is usually too time consuming to look at the whole population.

C

Which of the following is a discrete quantitative variable? A) the volume of water released from a dam B) the Dow Jones Industrial Average C) the number of employees of an insurance company D) the distance you drove yesterday

C

Which of the following statements about the median is not true? A) It is a measure of central tendency. B) It is equal to the mode in bell-shaped "normal" distributions. C) It is more affected by extreme values than the arithmetic mean. D) It is equal to Q2.

C

A summary measure that is computed to describe a characteristic from only a sample of the population is called A) the scientific method. B) a census. C) a parameter. D) a statistic.

D

If a particular batch of data is approximately normally distributed, we would find that approximately A) 19 of every 20 observations would fall between plusminus2 standard deviations around the mean. B) 2 of every 3 observations would fall between plusminus1 standard deviation around the mean. C) 4 of every 5 observations would fall between plusminus1.28 standard deviations around the mean. D) all of the above

D

Researchers are concerned that the weight of the average American school child is increasing, implying, among other things, that children's clothing should be manufactured and marketed in larger sizes. If X is the weight of school children sampled in a nationwide study, then X is an example of A) a parameter. B) a discrete random variable. C) a categorical random variable. D) a continuous random variable.

D

The collection of all possible events is called A) a simple probability. B) the null set. C) a joint probability. D) a sample space.

D

The employees of a company were surveyed on questions regarding their educational background and marital status. Of the 600 employees, 400 had college degrees, 100 were single, and 60 were single college graduates. The probability that an employee of the company is single or has a college degree is: A) 0.25 B) 0.10 C) 0.667 D) 0.733

D

Which of the following is most likely a population as opposed to a sample? A) the first 5 students completing an assignment B) respondents to a newspaper survey C) every third person to arrive at the bank D) registered voters in a county

D

Which of the following sampling methods is a probability sample? A) chunk B) quota sample C) judgment sample D) stratified sample

D

Which of the following statistics is NOT a measure of central tendency? A) arithmetic mean B) mode C) median D) Q3

D