DA0-002 Data Analysis Practice Question
A dataset contains a column 'Age' with values: [22, 25, 25, 30, 35, 40, 45]. What is the interquartile range (IQR)?
⚠ Common exam trap
DA0-002 often tests quartile calculation with odd-numbered datasets — the trap is including the median in both halves, which shifts Q1 and Q3 and produces an incorrect IQR.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
15
The interquartile range (IQR) is Q3 minus Q1. For the dataset [22, 25, 25, 30, 35, 40, 45], the median is 30. Q1 is the median of the lower half [22, 25, 25] = 25. Q3 is the median of the upper half [35, 40, 45] = 40. IQR = 40 - 25 = 15.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
15
Why this is correct
Ordered values give Q1 at 25 and Q3 at 40, so IQR equals 40 minus 25, which is 15. This satisfies the stem by measuring the spread of the middle half of the dataset, excluding the lowest and highest values.
- ✗
10
Why it's wrong here
Ten equals the gap between Q1 (25) and the median (30), or between the median and Q3 (40), not the interquartile range. IQR spans Q1 to Q3, giving 40 − 25 = 15. Ten would be correct only if the question asked for a single quartile deviation from the median.
- ✗
20
Why it's wrong here
An IQR of 20 wrongly treats the full spread between the minimum (22) and maximum (45) as the middle-fifty range. IQR is Q3 minus Q1, which here is 40 − 25 = 15. The value 20 arises only if you misread the quartile boundaries, so it fails this dataset.
- ✗
25
Why it's wrong here
Twenty-five is the value of Q1 itself, not the distance between Q1 and Q3. IQR requires subtracting Q1 from Q3: 40 − 25 = 15. Reporting a quartile position rather than their difference answers a different question, such as identifying the lower quartile boundary.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This DA0-002 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DA0-002 exam.