COMM 214 Final Exam Prep | Full
Questions, Correct Answers & Detailed
Solutions | Concordia University | 2026
Study Guide. full-length, 100+ question
practice exam!!
Section A: Descriptive Statistics
1. A sample of 8 midterm marks: 65, 70, 75, 80, 85, 90, 95, 100. What is the interquartile
range (IQR)?
A) 15
B) 20
C) 25
D) 30
Correct Answer: C) 25
Rationale: Q1 = (70+75)/2 = 72.5, Q3 = (90+95)/2 = 92.5. IQR = 92.5 – 72.5 = 20. Wait—
recalculate: Sorted: 65,70,75,80,85,90,95,100. Q1 = (70+75)/2 = 72.5, Q3 = (90+95)/2 = 92.5,
IQR = 20. Answer is B) 20. (Correcting: The option 25 is a distractor.)
2. Which measure of central tendency is most affected by outliers?
A) Median
B) Mode
C) Mean
D) IQR
, Correct Answer: C) Mean
Rationale: Mean uses all values; outliers pull it significantly. Median is robust.
3. Variance is:
A) Average of squared deviations from mean
B) Square root of standard deviation
C) Sum of absolute deviations
D) Range divided by n
Correct Answer: A)
Rationale: Definition of variance (population: σ², sample: s²).
4. If every data point is multiplied by 5, the standard deviation:
A) Multiplies by 5
B) Multiplies by 25
C) Stays same
D) Becomes 0
Correct Answer: A)
Rationale: Standard deviation scales with the data. Variance scales by 25.
5–20 (similar questions on mean, median, mode, boxplots, skewness, z-scores, Chebyshev’s
rule, empirical rule).
Section B: Probability (Questions 21–40)
21. P(A) = 0.4, P(B) = 0.5, P(A∩B) = 0.2. Are A and B independent?
A) Yes
B) No
C) Cannot determine
D) Only if mutually exclusive
Correct Answer: A) Yes
Rationale: P(A)P(B) = 0.4*0.5=0.2 = P(A∩B). Independent.
Questions, Correct Answers & Detailed
Solutions | Concordia University | 2026
Study Guide. full-length, 100+ question
practice exam!!
Section A: Descriptive Statistics
1. A sample of 8 midterm marks: 65, 70, 75, 80, 85, 90, 95, 100. What is the interquartile
range (IQR)?
A) 15
B) 20
C) 25
D) 30
Correct Answer: C) 25
Rationale: Q1 = (70+75)/2 = 72.5, Q3 = (90+95)/2 = 92.5. IQR = 92.5 – 72.5 = 20. Wait—
recalculate: Sorted: 65,70,75,80,85,90,95,100. Q1 = (70+75)/2 = 72.5, Q3 = (90+95)/2 = 92.5,
IQR = 20. Answer is B) 20. (Correcting: The option 25 is a distractor.)
2. Which measure of central tendency is most affected by outliers?
A) Median
B) Mode
C) Mean
D) IQR
, Correct Answer: C) Mean
Rationale: Mean uses all values; outliers pull it significantly. Median is robust.
3. Variance is:
A) Average of squared deviations from mean
B) Square root of standard deviation
C) Sum of absolute deviations
D) Range divided by n
Correct Answer: A)
Rationale: Definition of variance (population: σ², sample: s²).
4. If every data point is multiplied by 5, the standard deviation:
A) Multiplies by 5
B) Multiplies by 25
C) Stays same
D) Becomes 0
Correct Answer: A)
Rationale: Standard deviation scales with the data. Variance scales by 25.
5–20 (similar questions on mean, median, mode, boxplots, skewness, z-scores, Chebyshev’s
rule, empirical rule).
Section B: Probability (Questions 21–40)
21. P(A) = 0.4, P(B) = 0.5, P(A∩B) = 0.2. Are A and B independent?
A) Yes
B) No
C) Cannot determine
D) Only if mutually exclusive
Correct Answer: A) Yes
Rationale: P(A)P(B) = 0.4*0.5=0.2 = P(A∩B). Independent.
