The correct answer is the DAX expression using CALCULATE with DATESINPERIOD, specifically CALCULATE(SUM(Sales[Amount]), DATESINPERIOD(Date[Date], MAX(Date[Date]), -12, MONTH)). This works because DATESINPERIOD dynamically shifts the filter context backward by 12 months from the latest date in the current filter context, creating a true rolling 12 months total that includes the current month. On the Microsoft Power BI Data Analyst PL-300 exam, this question tests your ability to distinguish between time intelligence functions for rolling calculations versus fixed periods like year-to-date or parallel comparisons. A common trap is confusing DATESINPERIOD with TOTALYTD or PARALLELPERIOD, which serve different purposes—TOTALYTD locks to the start of the year, while PARALLELPERIOD compares entire periods without accumulating. Remember the memory tip: “DATESINPERIOD rolls back, TOTALYTD rolls up.”
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 a data analyst for a retail company. You have a Power BI semantic model that includes a fact table named Sales with columns: Date, ProductID, StoreID, Quantity, and Amount. You also have dimension tables: Product, Store, and Date. The Date table is marked as a date table. You need to create a measure that calculates the running total of sales amount over the last 12 months, including the current month. The measure should be dynamic based on the filter context. Which DAX expression should you use?
Option A uses DATESINPERIOD with a -12 month offset, which correctly calculates a rolling 12-month total. Option B uses PARALLELPERIOD for parallel period comparison, not rolling total. Option C uses DATESBETWEEN with a fixed start date, which is not dynamic. Option D uses TOTALYTD which calculates year-to-date, not rolling 12 months.
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.
DATESINPERIOD shifts the date range back 12 months from the last date in context, creating a rolling 12-month total.
Related concept
Read the scenario before looking for a memorised answer.
✗
TOTALYTD(SUM(Sales[Amount]), Date[Date])
Why it's wrong here
TOTALYTD calculates year-to-date, not rolling 12 months.
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: CALCULATE(SUM(Sales[Amount]), DATESINPERIOD(Date[Date], MAX(Date[Date]), -12, MONTH)) — Option A uses DATESINPERIOD with a -12 month offset, which correctly calculates a rolling 12-month total. Option B uses PARALLELPERIOD for parallel period comparison, not rolling total. Option C uses DATESBETWEEN with a fixed start date, which is not dynamic. Option D uses TOTALYTD which calculates year-to-date, not rolling 12 months.
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.
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Question Discussion
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