Exam 1 Flashcards
Which of the following is most likely a population as opposed to a sample?
The first 5 students completing an assignment
Registered voters in a county
Respondents to a newspaper survey
Every third person to arrive at the bank
Registered voters in a county
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 variable of interest in the study.
The age of an American pine tree in Yosemite National Forest
The number of American pine trees in Yosemite National Forest
The height of an American pine tree in Yosemite National Forest
The species of trees in Yosemite National Forest
The height of an American pine tree in Yosemite National Forest
Which of the following is a continuous quantitative (numerical) variable?
The number of gallons of milk sold at the local grocery store yesterday
The color of a student’s eyes
The amount of milk produced by a cow in one 24-hour period
The number of employees of an insurance company
The amount of milk produced by a cow in one 24-hour period
A summary measure that is computed to describe a characteristic of an entire population is called
a statistic.
the scientific method.
a census.
a parameter.
a parameter.
The universe or “totality of items or things” under consideration is called
a population.
a sample.
a parameter.
a statistic.
a population.
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.
All American pine trees, of any age, in the forest
The 25,000 adult American pine trees in the forest
All the adult American pine trees taller than 60 feet
The 250 randomly selected adult American pine trees
The 250 randomly selected adult American pine trees
The manager of the customer service division of a major consumer electronics company is interested in determining whether the customers who have purchased a DVD player made by the company over the past 12 months are satisfied with their products.The possible responses to the question “How many DVD players made by other manufacturers have you used?” are values from a
discrete random variable.
categorical random variable.
continuous random variable.
parameter.
discrete random variable.
The grade level (K-12) of a student is an example of a nominal scaled variable.
True
False
False
Marital status is an example of an ordinal scaled variable.
True
False
False
A sample is the portion of the universe that is selected for analysis.
True
False
True
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.
True
False
True
A Wall Street Journal poll asked 2,150 adults in the U.S. a series of questions to find out their view on the U.S. economy. The possible responses to the question “Are you 1. Currently employed, 2. Unemployed but actively looking for job, 3. Unemployed and quit looking for job?” result in
a nominal scale variable.
an interval scale variable.
a ratio scale variable.
an ordinal scale variable.
a nominal scale variable.
A statistics student found a reference in the campus library that contained the median family incomes for all 50 states. She would report her data as being collected using
a published source.
a random sample.
observational data.
a designed experiment.
a published source.
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?
Experimentation
Published sources
Surveying
Observation
Published sources
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 the last 3 years, with the following results.
x: 1 2 3 4 5
f: 14 18 12 5 1
How many total claims are represented in the sample?
50
15
250
111
111
A type of vertical bar chart in which the categories are plotted in the descending rank order of the magnitude of their frequencies is called a
contingency table.
stem-and-leaf display.
pie chart.
Pareto chart.
Pareto chart.
At a meeting of information systems officers for regional offices of a national company, a survey was taken to determine the number of employees the officers supervise in the operation of their departments, where X is the number of employees overseen by each information systems officer.
X: 1 2 3 4 5
f: 7 5 11 8 9
How many regional offices are represented in the survey results?
5
15
11
40
40
The width of each bar in a histogram corresponds to the
percentage of observations in each class.
differences between the boundaries of the class.
number of observations in each class.
midpoint of each class.
differences between the boundaries of the class.
Every spring semester, the School of Business coordinates a luncheon with local business leaders for graduating seniors, their families, and friends. Corporate sponsorship pays for the lunches of each of the seniors, but students have to purchase tickets to cover the cost of lunches served to guests they bring with them. The following histogram represents the attendance at the senior luncheon, where X is the number of guests each graduating senior invited to the luncheon and f is the number of graduating seniors in each category.
X: 0 1 2 3 4 5
f: 17 152 85 18 3 0
How many graduating seniors attended the luncheon?
388
4
275
152
275
A professor of economics at a small Texas university wanted to determine what year in school students were taking his tough economics course. Shown below is a pie chart of the results.
Freshman: 10%
Sophmores: 46%
Juniors: 30%
Seniors: 14%
What percentage of the class took the course prior to reaching their senior year?
86%
44%
54%
14%
86%
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: 3 4 5 6 7 8 9
Leaves: 2 0 0 1 0 2
4 3 1 2 1
4 1 5
7 2 6
8 3 6
9 4
9 5
9
What percentage of the respondents rated overall television quality with a rating of 80 or above?
100
0
4
96
4
The following are the duration in minutes of a sample of long-distance phone calls made within the continental United States reported by one long-distance carrier.
Time in Minutes: Relative Frequency:
0 but less than 5 0.37
5 but less than 10 0.22
10 but less than 15 0.15
15 but less than 20 0.10
20 but less than 25 0.07
25 but less than 30 0.07
30 or more 0.02
If 100 calls were sampled, ________ of them would have lasted less than 15 minutes.
74
None of these
10
26
74
You have collected data on the responses to two questions asked in a survey of 40 college students majoring in business. What is your gender? (Male = M; Female = F) and What is your major? (Accountancy = A; Computer Information Systems = C; Marketing = M). Which of the following is the best for presenting the data?
A contingency table
A Pareto chart
A time-series plot
A stem-and-leaf display
A contingency table
A sample of 200 students at a Big-Ten university was taken after the midterm to ask them whether they went bar hopping the weekend before the midterm or spent the weekend studying, and whether they did well or poorly on the midterm. The following table contains the result.
Did well Did Poorly
Study for Exam: 80 20
Went bar hopping: 30 70
Of those who went bar hopping the weekend before the midterm in the sample, ________ percent of them did well on the midterm.
27.27
30
15
55
30
In a contingency table, the number of rows and columns
must always be the same.
None of these
must add to 100%.
must always be 2.
None of these
Retailers are always interested in determining why a customer selected their store to make a purchase. A sporting goods retailer conducted a customer survey to determine why its customers shopped at the store. The results are shown in the bar chart below.
Prices: 20%
Merchandise: 50%
Convenience: 15%
Other: 15%
What proportion of the customers responded that they shopped at the store because of the merchandise or the convenience?
65%
50%
85%
35%
65%
The percentage distribution cannot be constructed from the frequency distribution directly.
True
False
False
The stem-and-leaf display below shows the result of a survey on 50 students on their satisfaction with their school with the higher scores represent higher level of satisfaction.
sample size: 50
mean: 71.06
median: 73.5
standard deviation: 14.13695
minimum: 41
maximum: 97
The level of satisfaction is concentrated around 75.
True
False
True
In right-skewed distributions, which of the following is the correct statement?
The distance from Q1 to Q2 is less than the distance from Q2 to Q3.
The mode is greater than the arithmetic mean.
The arithmetic mean is less than the median.
The distance from Q1 to Q2 is greater than the distance from Q2 to Q3.
The distance from Q1 to Q2 is less than the distance from Q2 to Q3.
Which of the following is not sensitive to extreme values?
The standard deviation
The interquartile range
The coefficient of variation
The range
The interquartile range
In a perfectly symmetrical bell-shaped “normal” distribution
the median equals the mode.
All of these.
the arithmetic mean equals the median.
the arithmetic mean equals the mode.
All of these.
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.
88.89
93.75
95.44
68.26
95.44
In perfectly symmetrical distributions, which of the following is not a correct statement?
The distance from Q1 to Q3 is half of the distance from the smallest to the largest observation.
The distance from Q1 to Q2 equals to the distance from Q2 to Q3.
The distance from the smallest observation to Q2 is the same as the distance from Q2 to the largest observation.
The distance from the smallest observation to Q1 is the same as the distance from Q3 to the largest observation.
The distance from Q1 to Q3 is half of the distance from the smallest to the largest observation.
Which measure of central tendency can be used for both numerical and categorical variables?
Z Score
Arithmetic mean
Median
Mode
Mode
Which of the following is sensitive to extreme values?
The 1st quartile
The arithmetic mean
The median
The interquartile range
The arithmetic mean
Which of the following statements about the median is not true?
It is more affected by extreme values than the arithmetic mean.
It is equal to the mode in bell-shaped “normal” distributions.
It is equal to Q2.
It is a measure of central tendency.
It is more affected by extreme values than the arithmetic mean.
Health care issues are receiving much attention in both academic and political arenas. A sociologist recently conducted a survey of citizens over 60 years of age whose net worth is too high to qualify for Medicaid. The ages of 25 senior citizens were as follows:
60 61 62 63 64 65 66 68 68 69 70 73 73 74 75 76 76 81 81 82 86 87 89 90 92
Identify which of the following is the correct statement.
The middle 50% of the senior citizens sampled are between 65.5 and 73.0 years of age.
One fourth of the senior citizens sampled are below 64 years of age.
25% of the senior citizens sampled are older than 81.5 years of age.
All of these are correct.
25% of the senior citizens sampled are older than 81.5 years of age.
Health care issues are receiving much attention in both academic and political arenas. A sociologist recently conducted a survey of citizens over 60 years of age whose net worth is too high to qualify for Medicaid. The ages of 25 senior citizens were as follows:
60 61 62 63 64 65 66 68 68 69 70 73 73 74 75 76 76 81 81 82 86 87 89 90 92
Determine which of the following is the correct statement.
The mean age of senior citizens sampled is 73.5 years of age.
All of these are correct.
One fourth of the senior citizens sampled are below 65.5 years of age.
The middle 50% of the senior citizens sampled are between 65.5 and 73.0 years of age.
One fourth of the senior citizens sampled are below 65.5 years of age.
In left-skewed distributions, which of the following is the correct statement?
The distance from Q1 to Q3 is twice the distance from the Q1 to Q2.
The distance from Q1 to Q2 is smaller than the distance from Q2 to Q3.
The distance from the smallest observation to Q2 is less than the distance from Q2 to the largest observation.
The distance from the smallest observation to Q1 is larger than the distance from Q3 to the largest observation.
The distance from the smallest observation to Q1 is larger than the distance from Q3 to the largest observation.
Which of the following statistics is not a measure of central tendency?
Mode
Median
Arithmetic mean
Q3
Q3
In a right-skewed distribution
None of these.
the median is greater than the arithmetic mean.
the median equals the arithmetic mean.
the median is less than the arithmetic mean.
the median is less than the arithmetic mean.
In a perfectly symmetrical distribution
the median equals the arithmetic mean.
the variance equals the standard deviation.
the range equals the interquartile range.
the interquartile range equals the arithmetic mean.
the median equals the arithmetic mean.
In right-skewed distributions, the distance from Q3 to the largest value is greater than the distance from the smallest observation to Q1.
True
False
True
The five-number summary consists of the smallest value, the first quartile, the median, the third quartile, and the largest value.
True
False
True
The Z score of a value measures how many standard deviations the value is from the mean.
True
False
True
In a set of numerical data, the value for Q2 is always halfway between Q1 and Q3.
True
False
False
The median of the values 3.4, 4.7, 1.9, 7.6, and 6.5 is 1.9.
True
False
False
The line drawn within the box of the boxplot always represents the median.
True
False
True
A population with 200 elements has an arithmetic mean of 10. From this information, it can be shown that the population standard deviation is 15.
True
False
False
In exploratory data analysis, a boxplot can be used to illustrate the median, quartiles, and extreme values.
True
False
True
The following data was gathered from the Virginia Department of Health’s (VDH) website on 2/11/23. The table below shows the reported number of people in Virginia infected with Covid-19 across various age groups since the beginning of the pandemic. Additionally, the table below shows how many deaths occurred from those who reported having Covid-19.
Age Group: # of cases: # of Deaths:
0-9 years 380,000 50
10-19 years 532,000 30
20-29 years 784,000 200
30-39 years 740,000 600
40-49 years 634,000 1,500
50-59 years 599,000 4,100
60-69 years 434,000 8,200
70-79 years 252,000 12,000
80+ years 161,000 19,500
SUM 4,516,000 46,180
When considering number of deaths, the median for age would lie in the __________ age group.
50-59
40-49
60-69
80+
70-79
70-79
If two events are mutually exclusive and collectively exhaustive, what is the probability that one or the other occurs?
0.50
1.00
0
Cannot be determined from the information given
1.00
If two events are collectively exhaustive, what is the probability that both occur at the same time?
1.00
0.50
0
Cannot be determined from the information given
Cannot be determined from the information given
If two equally likely events A and B are mutually exclusive, what is the probability that event A occurs?
Cannot be determined from the information given
1.00
0
0.50
Cannot be determined from the information given
If two events are independent, what is the probability that they both occur?
0.50
1.00
0
Cannot be determined from the information given
Cannot be determined from the information given
If the outcome of event A is not affected by event B, then events A and B are said to be
None of these.
mutually exclusive.
independent.
collectively exhaustive.
independent.
A business venture can result in the following outcomes (with their corresponding chance of occurring in parentheses): Highly Successful (10%), Successful (25%), Break Even (25%), Disappointing (20%), and Highly Disappointing (?). If these are the only outcomes possible for the business venture, what is the chance that the business venture will be considered Highly Disappointing?
10%
15%
20%
25%
20%
A survey of banks revealed the following distribution for the interest rate being charged on a home loan (based on a 30-year mortgage with a 10% down payment).
Intrest rate: Probability:
4.90% to 4.99% 0.12
5.00% to 5.09% 0.23
5.10% to 5.19% 0.24
5.20% to 5.29% 0.35
5.30% and above 0.06
If a bank is selected at random from this distribution, what is the chance that the interest rate charged on a home loan will exceed 5.19%?
0.06
1.00
0.59
0.41
0.41
The employees of a company were surveyed on questions regarding their educational background (college degree or no college degree) and marital status (single or married). 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 married and has a college degree is
0.833.
0.0667.
0.667.
0.567.
0.567
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 house sales will increase but interest rates will not during the next 6 months is
0.065.
0.89.
0.51.
0.15.
0.15
The probability that a new advertising campaign will increase sales is assessed as being 0.80. The probability that the cost of developing the new ad campaign can be kept within the original budget allocation is 0.40. Assuming that the two events are independent, the probability that the cost is kept within budget or the campaign will increase sales is
0.32.
0.88.
0.68.
0.20.
0.88
According to a survey of American households, the probability that the residents own 2 cars if annual household income is over $50,000 is 80%. Of the households surveyed, 60% had incomes over $50,000 and 70% had 2 cars. The probability that annual household income is over $50,000 if the residents of a household own 2 cars is
0.42.
0.69.
0.48.
0.50.
0.69
A company has 2 machines that produce widgets. An older machine produces 23% defective widgets, while the new machine produces only 8% defective widgets. In addition, the new machine produces 3 times as many widgets as the older machine does. Given that a widget was produced by the new machine, what is the probability it is not defective?
0.92
0.06
0.94
0.50
0.92
A company has 2 machines that produce widgets. An older machine produces 23% defective widgets, while the new machine produces only 8% defective widgets. In addition, the new machine produces 3 times as many widgets as the older machine does. Given a randomly chosen widget was tested and found to be defective, what is the probability it was produced by the new machine?
0.489
0.511
0.15
0.08
0.511
Mothers Against Drunk Driving is a very visible group whose main focus is to educate the public about the harm caused by drunk drivers. A study was recently done that emphasized the problem we all face with drinking and driving. Four hundred accidents that occurred on a Saturday night were analyzed. Two items noted were the number of vehicles involved and whether alcohol played a role in the accident. The numbers are shown below:
# of vehicals: Did alchol play a role? 1 2 3 total
yes 50 100 20 170
no 25 175 30 230
total 75 275 50 400
Given that multiple vehicles were involved, what proportion of accidents involved alcohol?
120/400 or 30%
120/170 or 70.59%
120/230 or 52.17%
120/325 or 36.92%
120/325 or 36.92%
An alcohol awareness task force at a Big-Ten university sampled 200 students after the midterm to ask them whether they went bar hopping the weekend before the midterm or spent the weekend studying, and whether they did well or poorly on the midterm. The following result was obtained.
did well did poorly studied: 80 20 went to the bar: 30 70
The events “Did Well on Midterm” and “Studying for Exam” are?
collective exhaustive.
dependent.
mutually exclusive.
None of these.
dependent
The collection of all the possible events is called a sample space.
True
False
True
If P(A and B) = 1, then A and B must be mutually exclusive.
True
False
False
You know that the probability of a randomly selected student cheating on an exam is 1% (Event 1). You also know that the probability of a randomly selected student cheating on an exam knowing that his/her fellow classmate is cheating on the exam is also 1% (Event 2). Which of the following is true about the 2 events?
They are independent.
None of these.
They are mutually exclusive.
They are collectively exhaustive.
They are independent.
A random sample of computer users were asked which browser they primarily relied on for surfing the Internet and whether this browser was installed on a desktop or laptop computer. The following contingency table shows these results.
Browser Desktop laptop
Internet Explorer 18 56
Firefox 7 37
Chrome 24 77
Safari 3 18
Other 3 7
The probability that a randomly selected person from this sample used Internet Explorer OR Chrome is ________.
0.651
0.000
0.814
0.700
0.585
0.700
A random sample of computer users were asked which browser they primarily relied on for surfing the Internet and whether this browser was installed on a desktop or laptop computer. The following contingency table shows these results.
Browser Desktop laptop
Internet Explorer 18 56
Firefox 7 37
Chrome 24 77
Safari 3 18
Other 3 7
The probability that a randomly selected person from this sample used Internet Explorer AND Chrome is ________.
0.814
0.000
0.651
0.585
0.700
0.000
