, BUSI 230 — WEEK 4 EXAM
Introduction to Probability and Statistics
Liberty University
100-Question Independent Practice Examination
2026/2027 Edition
Original early-course review emphasizing descriptive statistics, probability rules, counting methods, and discrete
distributions. Week 4 assessment labels and coverage may differ by course section.
Data and descriptive statistics
1. Classify the variable “number of returned packages” in an order database.
A) Nominal category
B) Continuous quantitative variable
C) Discrete quantitative variable
D) Ordinal category
Correct Answer: C) Discrete quantitative variable
Rationale: Counts take nonnegative integer values. Continuous quantities can occupy intervals, while nominal and
ordinal variables express categories rather than counts.
2. A retailer records customer satisfaction as poor, fair, good, or excellent. What measurement level
applies?
A) Ordinal
B) Ratio
C) Nominal
D) Interval
Correct Answer: A) Ordinal
Rationale: Satisfaction categories have a meaningful order, but their spacings are not demonstrated equal. Nominal
categories have no inherent rank; interval and ratio scales use numerical distances.
3. A sample excludes every customer who did not have internet access. What risk is most immediate?
A) Stratification gain
B) Perfect precision
C) Randomization success
D) Undercoverage bias
Correct Answer: D) Undercoverage bias
Rationale: An entire segment of the target population cannot enter the sampling frame. Extra responses from
connected customers cannot correct that systematic omission.
4. What feature distinguishes a randomized experiment from a purely observational comparison?
A) Researchers use a graph
B) Researchers record two variables
C) Researchers randomly assign an intervention
D) Researchers compute a median
Correct Answer: C) Researchers randomly assign an intervention
BUSI 230 | Week 4 | Independent Practice | 2026/2027 1
, Rationale: Random assignment determines exposure rather than merely observing naturally chosen exposure. It helps
balance confounding and strengthens causal inference.
5. For a highly right-skewed salary distribution, what measure best describes the typical employee?
A) Arithmetic mean
B) Variance
C) Median
D) Range
Correct Answer: C) Median
Rationale: The median is resistant to a few very large salaries, whereas the mean is pulled upward by outliers. Range
and variance describe dispersion rather than center.
6. A boxplot shows one point far beyond its upper whisker. What should the analyst conclude first?
A) Delete the observation without checking
B) Investigate a potentially unusual observation
C) Conclude a data-entry error is certain
D) Conclude the population is normal
Correct Answer: B) Investigate a potentially unusual observation
Rationale: A point beyond the whisker flags an unusual value under the selected boxplot convention. It need not be
erroneous and should be examined before any exclusion decision.
7. A correlation of −0.85 between advertising price and units sold indicates what?
A) A strong negative linear association
B) No linear association
C) A strong positive linear association
D) A proven causal effect
Correct Answer: A) A strong negative linear association
Rationale: Correlation near negative one indicates the two variables tend to move in opposite directions along a line. It
does not independently establish causation.
8. A statistician selects every tenth invoice after choosing a random starting invoice. Identify the sample
design.
A) Cluster sampling
B) Voluntary-response sampling
C) Convenience sampling
D) Systematic sampling
Correct Answer: D) Systematic sampling
Rationale: Systematic selection combines a random start with a fixed interval. Cluster sampling selects groups;
convenience and voluntary sampling do not follow this selection rule.
Probability principles
9. Two events have no outcomes in common. What relationship describes them?
A) Independent whenever both have positive probability
B) Mutually exclusive
C) Complementary in every case
D) Equally likely
BUSI 230 | Week 4 | Independent Practice | 2026/2027 2
Introduction to Probability and Statistics
Liberty University
100-Question Independent Practice Examination
2026/2027 Edition
Original early-course review emphasizing descriptive statistics, probability rules, counting methods, and discrete
distributions. Week 4 assessment labels and coverage may differ by course section.
Data and descriptive statistics
1. Classify the variable “number of returned packages” in an order database.
A) Nominal category
B) Continuous quantitative variable
C) Discrete quantitative variable
D) Ordinal category
Correct Answer: C) Discrete quantitative variable
Rationale: Counts take nonnegative integer values. Continuous quantities can occupy intervals, while nominal and
ordinal variables express categories rather than counts.
2. A retailer records customer satisfaction as poor, fair, good, or excellent. What measurement level
applies?
A) Ordinal
B) Ratio
C) Nominal
D) Interval
Correct Answer: A) Ordinal
Rationale: Satisfaction categories have a meaningful order, but their spacings are not demonstrated equal. Nominal
categories have no inherent rank; interval and ratio scales use numerical distances.
3. A sample excludes every customer who did not have internet access. What risk is most immediate?
A) Stratification gain
B) Perfect precision
C) Randomization success
D) Undercoverage bias
Correct Answer: D) Undercoverage bias
Rationale: An entire segment of the target population cannot enter the sampling frame. Extra responses from
connected customers cannot correct that systematic omission.
4. What feature distinguishes a randomized experiment from a purely observational comparison?
A) Researchers use a graph
B) Researchers record two variables
C) Researchers randomly assign an intervention
D) Researchers compute a median
Correct Answer: C) Researchers randomly assign an intervention
BUSI 230 | Week 4 | Independent Practice | 2026/2027 1
, Rationale: Random assignment determines exposure rather than merely observing naturally chosen exposure. It helps
balance confounding and strengthens causal inference.
5. For a highly right-skewed salary distribution, what measure best describes the typical employee?
A) Arithmetic mean
B) Variance
C) Median
D) Range
Correct Answer: C) Median
Rationale: The median is resistant to a few very large salaries, whereas the mean is pulled upward by outliers. Range
and variance describe dispersion rather than center.
6. A boxplot shows one point far beyond its upper whisker. What should the analyst conclude first?
A) Delete the observation without checking
B) Investigate a potentially unusual observation
C) Conclude a data-entry error is certain
D) Conclude the population is normal
Correct Answer: B) Investigate a potentially unusual observation
Rationale: A point beyond the whisker flags an unusual value under the selected boxplot convention. It need not be
erroneous and should be examined before any exclusion decision.
7. A correlation of −0.85 between advertising price and units sold indicates what?
A) A strong negative linear association
B) No linear association
C) A strong positive linear association
D) A proven causal effect
Correct Answer: A) A strong negative linear association
Rationale: Correlation near negative one indicates the two variables tend to move in opposite directions along a line. It
does not independently establish causation.
8. A statistician selects every tenth invoice after choosing a random starting invoice. Identify the sample
design.
A) Cluster sampling
B) Voluntary-response sampling
C) Convenience sampling
D) Systematic sampling
Correct Answer: D) Systematic sampling
Rationale: Systematic selection combines a random start with a fixed interval. Cluster sampling selects groups;
convenience and voluntary sampling do not follow this selection rule.
Probability principles
9. Two events have no outcomes in common. What relationship describes them?
A) Independent whenever both have positive probability
B) Mutually exclusive
C) Complementary in every case
D) Equally likely
BUSI 230 | Week 4 | Independent Practice | 2026/2027 2
