MATH 3339 ULTIMATE SUCCESS QUESTIONS
AND ANSWERS | 2026 UPDATE | WITH
COMPLETE SOLUTIONS.
Descriptive Statistics & Data Visualization
1. Which of the following is NOT a measure of central tendency?
A) Mean
B) Median
C) Mode
D) Standard Deviation
Correct Answer: D
Rationale: Standard deviation measures the spread or variability of a dataset,
not its center. Mean, median, and mode are all measures of central tendency.
2. The interquartile range (IQR) is defined as:
A) The range of the middle 50% of the data
B) The difference between the maximum and minimum
C) The average of the squared deviations
D) The 50th percentile
,Correct Answer: A
Rationale: The IQR is Q3 – Q1 and represents the spread of the central 50% of
observations. It is robust to outliers.
3. If every value in a dataset is multiplied by 3, what happens to the standard
deviation?
A) It is multiplied by 3
B) It is multiplied by 9
C) It remains unchanged
D) It is divided by 3
Correct Answer: A
Rationale: The standard deviation scales linearly with the data. Multiplying all
values by a constant c multiplies the standard deviation by |c|.
4. A histogram is most appropriate for:
A) Displaying the relationship between two categorical variables
B) Showing the distribution of a continuous variable
C) Comparing proportions across categories
D) Displaying the five-number summary
Correct Answer: B
Rationale: Histograms are used to visualize the distribution (shape, center,
spread) of a single continuous variable.
5. Which of the following is resistant to outliers?
,A) Mean
B) Standard deviation
C) Range
D) Median
Correct Answer: D
Rationale: The median is robust because it depends only on the middle order
statistic(s), not on the magnitude of extreme values.
6. A boxplot displays which of the following?
A) Mean and standard deviation
B) Five-number summary
C) All individual data points
D) Frequency of each value
Correct Answer: B
Rationale: A boxplot shows the minimum, Q1, median, Q3, and maximum (or
their outlier-adjusted versions).
7. If a distribution is skewed right, the mean is typically:
A) Less than the median
B) Greater than the median
C) Equal to the median
D) Unaffected by the skew
Correct Answer: B
, Rationale: In a right-skewed distribution, the tail pulls the mean toward the
larger values, so mean > median.
8. The variance of a sample is calculated by dividing the sum of squared
deviations by:
A) n
B) n – 1
C) n + 1
D) n – 2
Correct Answer: B
Rationale: Using n – 1 (degrees of freedom) provides an unbiased estimate of
the population variance.
9. Which measure of spread is expressed in the same units as the original
data?
A) Variance
B) Standard deviation
C) Coefficient of variation
D) Mean absolute deviation
Correct Answer: B
Rationale: Standard deviation is the square root of variance and thus has the
same units as the data.
10. A stem-and-leaf plot preserves:
A) Only the median
AND ANSWERS | 2026 UPDATE | WITH
COMPLETE SOLUTIONS.
Descriptive Statistics & Data Visualization
1. Which of the following is NOT a measure of central tendency?
A) Mean
B) Median
C) Mode
D) Standard Deviation
Correct Answer: D
Rationale: Standard deviation measures the spread or variability of a dataset,
not its center. Mean, median, and mode are all measures of central tendency.
2. The interquartile range (IQR) is defined as:
A) The range of the middle 50% of the data
B) The difference between the maximum and minimum
C) The average of the squared deviations
D) The 50th percentile
,Correct Answer: A
Rationale: The IQR is Q3 – Q1 and represents the spread of the central 50% of
observations. It is robust to outliers.
3. If every value in a dataset is multiplied by 3, what happens to the standard
deviation?
A) It is multiplied by 3
B) It is multiplied by 9
C) It remains unchanged
D) It is divided by 3
Correct Answer: A
Rationale: The standard deviation scales linearly with the data. Multiplying all
values by a constant c multiplies the standard deviation by |c|.
4. A histogram is most appropriate for:
A) Displaying the relationship between two categorical variables
B) Showing the distribution of a continuous variable
C) Comparing proportions across categories
D) Displaying the five-number summary
Correct Answer: B
Rationale: Histograms are used to visualize the distribution (shape, center,
spread) of a single continuous variable.
5. Which of the following is resistant to outliers?
,A) Mean
B) Standard deviation
C) Range
D) Median
Correct Answer: D
Rationale: The median is robust because it depends only on the middle order
statistic(s), not on the magnitude of extreme values.
6. A boxplot displays which of the following?
A) Mean and standard deviation
B) Five-number summary
C) All individual data points
D) Frequency of each value
Correct Answer: B
Rationale: A boxplot shows the minimum, Q1, median, Q3, and maximum (or
their outlier-adjusted versions).
7. If a distribution is skewed right, the mean is typically:
A) Less than the median
B) Greater than the median
C) Equal to the median
D) Unaffected by the skew
Correct Answer: B
, Rationale: In a right-skewed distribution, the tail pulls the mean toward the
larger values, so mean > median.
8. The variance of a sample is calculated by dividing the sum of squared
deviations by:
A) n
B) n – 1
C) n + 1
D) n – 2
Correct Answer: B
Rationale: Using n – 1 (degrees of freedom) provides an unbiased estimate of
the population variance.
9. Which measure of spread is expressed in the same units as the original
data?
A) Variance
B) Standard deviation
C) Coefficient of variation
D) Mean absolute deviation
Correct Answer: B
Rationale: Standard deviation is the square root of variance and thus has the
same units as the data.
10. A stem-and-leaf plot preserves:
A) Only the median
