The correct answer is CALCULATE(SUM(Sales[SalesAmount]), Sales[CurrencyCode] = "USD"). This DAX measure works because CALCULATE modifies the filter context of the calculation, allowing you to apply a specific condition—here, filtering the SUM of SalesAmount to only rows where CurrencyCode equals "USD"—while leaving the rest of the data model untouched. On the Microsoft Power BI Data Analyst PL-300 exam, this pattern tests your understanding of context transition and filter propagation, a core skill for creating dynamic measures. A common trap is trying to use SUM with a simple IF or FILTER inside it, which either fails or returns incorrect totals; CALCULATE is the only function that properly overrides existing filters. For a memory tip, remember that CALCULATE is like a "filter funnel"—it pours your aggregation through a specific condition, so when you need to isolate a currency, always start with CALCULATE and then your filter expression.
PL-300 Prepare the data Practice Question
This PL-300 practice question tests your understanding of prepare 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 preparing data in Power BI Desktop. You have a table that includes a 'SalesAmount' column and a 'CurrencyCode' column. You need to create a measure that calculates the total sales amount in USD only, filtering out other currencies. Which DAX expression should you use?
Option B is correct because it uses CALCULATE to modify the filter context, applying a filter that restricts the SUM of Sales[SalesAmount] to only rows where Sales[CurrencyCode] equals 'USD'. This is the standard DAX pattern for conditional aggregation in Power BI.
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.
Adding zero is unnecessary and does not affect filtering.
✗
SUM(Sales[SalesAmount])
Why it's wrong here
This sums all sales without filtering by currency.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose SUMX (Option A) because they think they need to explicitly filter rows before summing, not realizing that CALCULATE with a simple filter is the more efficient and correct DAX pattern for this scenario.
Detailed technical explanation
How to think about this question
CALCULATE is a context transition function that evaluates an expression in a modified filter context; when a simple predicate like Sales[CurrencyCode] = 'USD' is passed as a filter argument, it implicitly wraps it in a FILTER over the entire table. This is more efficient than SUMX with an explicit FILTER because CALCULATE leverages the storage engine's ability to push filters down to the VertiPaq engine, reducing query execution time in large datasets.
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.
TExam Day Tips
→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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Prepare the data — This question tests Prepare 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[SalesAmount]), Sales[CurrencyCode] = "USD") — Option B is correct because it uses CALCULATE to modify the filter context, applying a filter that restricts the SUM of Sales[SalesAmount] to only rows where Sales[CurrencyCode] equals 'USD'. This is the standard DAX pattern for conditional aggregation in Power BI.
What should I do if I get this PL-300 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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