DA0-002 Data Acquisition and Preparation Practice Question
A data analyst is using the IQR method to identify outliers in a dataset. The first quartile (Q1) is 25 and the third quartile (Q3) is 45. What is the upper bound for identifying outliers?
⚠ Common exam trap
DA0-002 often tests the IQR calculation. Candidates might forget the 1.5 multiplier or miscalculate the IQR, leading to wrong bounds. The trap is using the wrong formula or arithmetic error.
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
✓
75
The IQR method defines outliers as values below Q1 - 1.5*IQR or above Q3 + 1.5*IQR. Here, Q1=25, Q3=45, so IQR = 45-25 = 20. The upper bound is Q3 + 1.5*IQR = 45 + 1.5*20 = 45 + 30 = 75. Therefore, any value above 75 is considered an outlier.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
85
Why it's wrong here
The IQR is 20, giving an upper fence of 45 + 30 = 75, so 85 exceeds it. Doubling the IQR to 40 and adding it to Q3 is tempting because 3 × IQR is the extreme-outlier threshold, but the standard upper bound uses 1.5 × IQR.
- ✗
65
Why it's wrong here
The upper bound is Q3 plus 1.5×IQR, so 45 + 1.5×20 = 75, not 65. Subtracting 1.5×IQR from Q1 gives the lower bound of 5; 65 instead applies a 1.0 multiplier, which is used for identifying extreme outliers only under some conventions.
- ✓
75
Why this is correct
The IQR is Q3 minus Q1, giving 20. The upper outlier bound is Q3 plus 1.5 times the IQR, so 45 + 30 = 75. This satisfies the stem's request for the upper bound using the IQR method.
- ✗
55
Why it's wrong here
The IQR is 20, so the upper fence is Q3 + 1.5 × IQR = 45 + 30 = 75, not 55. Adding only half the IQR to Q3 is tempting because it resembles a tighter fence, but the standard Tukey rule uses 1.5 times the IQR.
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.