Top 10 Power BI DAX Questions for PL-300 Exam (2025)

Introduction

If you’re preparing for the PL-300 Power BI Certification, one topic you must master is DAX (Data Analysis Expressions).
DAX is the language that gives Power BI its analytical power — helping you create measures, KPIs, and insights that go far beyond standard visuals.

At Datavetaa, we’ve trained hundreds of students in Pune and Wakad to not only clear the PL-300 exam but to apply DAX confidently in real projects.
In this guide, we cover the Top 10 DAX Questions frequently asked in both PL-300 exams and Power BI interviews — with examples and explanations.

🧠 1. What is DAX and why is it important?

Answer:
DAX (Data Analysis Expressions) is a formula language used in Power BI, Excel, and Analysis Services.
It allows you to create calculated columns, measures, and custom calculations on your data model.

Example:

Total Sales = SUM(Sales[SalesAmount])

Why it matters:
In the PL-300 exam, DAX is tested heavily under Data Modeling and Visualize & Analyze Data sections.

📘 Learn DAX fundamentals step-by-step in our Ultimate Guide to Power BI 2025.

⚙️ 2. What’s the difference between Calculated Column and Measure?

Feature Calculated Column Measure Storage Stored in the model Calculated dynamically Performance Slower, uses memory Faster, processed at query time Example Profit = [Sales] - [Cost] Total Profit = SUM(Sales[Sales]) - SUM(Sales[Cost])

💡 Tip: For PL-300, remember — use measures wherever possible to keep reports optimized.

📊 3. What does the CALCULATE() function do?

Answer:
CALCULATE() modifies the filter context of a measure. It’s one of the most powerful DAX functions.

Example:

Sales for 2025 = CALCULATE(SUM(Sales[Amount]), Sales[Year] = 2025)

This function re-evaluates the calculation under a new filter — essential for time intelligence and conditional KPIs.

🧩 4. Explain the FILTER() function with an example.

FILTER() returns a table that meets a given condition — often used inside CALCULATE().

Example:

High Value Customers =
CALCULATE(
    COUNTROWS(Sales),
    FILTER(Sales, Sales[Amount] > 100000)
)

This will count only transactions where sales exceeded ₹1,00,000.

⏱️ 5. What is ALL() and why is it used?

ALL() removes filters applied on a column or table — perfect for comparisons and percentages.

Example:

% of Total Sales =
DIVIDE(SUM(Sales[Amount]), CALCULATE(SUM(Sales[Amount]), ALL(Sales)))

✅ PL-300 Tip: Expect at least one scenario-based question using ALL() or REMOVEFILTERS().

📈 6. What are Time Intelligence Functions in DAX?

Time intelligence functions analyze data over time — like YoY growth or monthly averages.

Common examples:

YTD Sales = TOTALYTD(SUM(Sales[Amount]), 'Date'[Date])
Prev Year Sales = CALCULATE(SUM(Sales[Amount]), SAMEPERIODLASTYEAR('Date'[Date]))

🧭 To master these, check out our PL-300 Power BI Certification Guide 2025.

🪄 7. What’s the difference between SUM() and SUMX()?

Function Purpose Example SUM() Adds up a single column SUM(Sales[Amount]) SUMX() Iterates through each row to calculate an expression SUMX(Sales, Sales[Quantity] * Sales[Price])

🧠 Remember: X functions (like SUMX, AVERAGEX) are iterators — they process row by row.

🔍 8. How do you handle BLANK values in DAX?

Use the COALESCE() or IF() function to replace blanks.

Example:

Actual Sales = COALESCE(SUM(Sales[Amount]), 0)

✅ Appears often in both exam questions and real Power BI dashboards.

📋 9. What is Context Transition in DAX?

Context transition occurs when row context (like in a calculated column) is converted into filter context (like in a measure).
This happens when you use CALCULATE() — one of the trickier PL-300 topics.

Example:

Profit Margin = DIVIDE([Total Profit], [Total Sales])

Here, the measure converts row context dynamically during evaluation.

🧮 10. Write a DAX formula to find the top-performing product.

Example:

Top Product =
TOPN(
    1,
    SUMMARIZE(Sales, Products[ProductName], "TotalSales", SUM(Sales[Amount])),
    [TotalSales],
    DESC
)

This formula retrieves the product with the highest total sales.

✅ Final Tips for PL-300 DAX Preparation

• Practice with real datasets in Power BI Desktop.

• Focus on filter context, iterators, and time intelligence.

• Use Microsoft Learn mock exams to understand question style.

• Revise all concepts with offline sessions — Best Power BI Training in Pune 2025.

🏁 Final Thoughts

DAX isn’t just a set of functions — it’s the logic that drives all analytics in Power BI.
If you can think in DAX, you can think like a data analyst.

At Datavetaa, we simplify DAX using real business cases and hands-on practice, making you confident for both PL-300 certification and Power BI job interviews.

🚀 Ready to become a DAX expert?
👉 Start with our Power BI + Advanced SQL Training in Pune
or explore the Ultimate Guide to Power BI 2025.