The answer is to create a relationship between Sales and Product on ProductID, and use Product[Category] in the measure. This approach is correct because it leverages Power BI’s star schema design, where the Product table acts as a dimension table with Category as an attribute, enabling efficient aggregations without inflating the model size. For the PL-300 exam, this tests your understanding of how to optimize average sales per category performance optimization by avoiding calculated columns or summarized tables that increase memory usage or lose granularity. A common trap is thinking a calculated column in the Sales table is needed, but that bloats the model unnecessarily. Instead, rely on the existing relationship to filter and aggregate across the 20 categories directly. Memory tip: “Dimension filters, fact tables measure—never duplicate the dimension’s treasure.”
PL-300 Model the data Practice Question
This PL-300 practice question tests your understanding of model the data. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You are designing a Power BI semantic model for a retail company. The model includes a Sales table (50 million rows) and a Product table (10,000 rows). You need to create a measure that calculates the average sales amount per product category. The Product table has a column 'Category' with 20 distinct values. To optimize performance, what should you do?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a relationship between Sales and Product on ProductID, and use Product[Category] in the measure.
Option A is correct because marking the Product table as a dimension table with 'Category' as a column allows for efficient aggregations. Option B is wrong because a calculated column in Sales would increase model size. Option C is wrong because a calculated category table would be redundant. Option D is wrong because summarizing the Sales table loses granularity.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Add a calculated column to Sales that looks up the category using RELATED.
Why it's wrong here
Calculated columns increase storage and refresh time.
✗
Summarize the Sales table to the category level in Power Query.
Why it's wrong here
Summarizing loses detail needed for other analyses.
✗
Create a separate calculated table for categories and link it to Sales.
Why it's wrong here
This adds unnecessary complexity and table scans.
✓
Create a relationship between Sales and Product on ProductID, and use Product[Category] in the measure.
Why this is correct
This leverages the star schema and efficient query plans.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which PL-300 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Model the data — This question tests Model the data — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a relationship between Sales and Product on ProductID, and use Product[Category] in the measure. — Option A is correct because marking the Product table as a dimension table with 'Category' as a column allows for efficient aggregations. Option B is wrong because a calculated column in Sales would increase model size. Option C is wrong because a calculated category table would be redundant. Option D is wrong because summarizing the Sales table loses granularity.
What should I do if I get this PL-300 question wrong?
Identify which PL-300 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This PL-300 practice question is part of Courseiva's free Microsoft 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 PL-300 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.