First Power BI report - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ visualization

intermediate

Identify the best visual for showing sales trends over time

You have monthly sales data for the last year. Which Power BI visual should you use to clearly show the sales trend over time?

A Line Chart

B Pie Chart

C Stacked Bar Chart

D Card Visual

💡 Hint

Think about which visual best shows changes over time.

A Line Chart is best for showing trends over time because it connects data points in a continuous flow, making it easy to see increases or decreases month by month.

❓ dax_lod_result

intermediate

Calculate total sales for a specific product category

Given a sales table with columns: ProductCategory, SalesAmount, and Date, which DAX measure correctly calculates total sales for the 'Electronics' category?

Power BI

Total Electronics Sales = CALCULATE(SUM(Sales[SalesAmount]), Sales[ProductCategory] = "Electronics")

A Total Electronics Sales = SUMX(FILTER(Sales, Sales[ProductCategory] = "Electronics"), Sales[SalesAmount])

B Total Electronics Sales = CALCULATE(SUM(Sales[SalesAmount]), Sales[ProductCategory] = "Electronics")

C Total Electronics Sales = SUM(Sales[SalesAmount]) WHERE Sales[ProductCategory] = "Electronics"

D Total Electronics Sales = SUM(Sales[SalesAmount]) + Sales[ProductCategory] = "Electronics"

💡 Hint

Use CALCULATE to filter the data before summing.

Option B uses CALCULATE with a filter condition correctly. Option B is valid DAX but less efficient. Option B and D are invalid syntax.

❓ data_modeling

advanced

Choose the best relationship type for a star schema

You have a fact table with sales data and several dimension tables like Products and Customers. What is the best relationship type to connect the fact table to dimension tables in Power BI?

A One-to-one relationship with no filtering

B Many-to-many relationship with bidirectional filtering

C One-to-many relationship with single direction filtering from dimension to fact

D Many-to-one relationship with filtering from fact to dimension

💡 Hint

Think about how data flows in a star schema from dimensions to facts.

In a star schema, dimension tables filter the fact table. This is done with a one-to-many relationship from dimension (one) to fact (many) with single direction filtering.

🎯 Scenario

advanced

Improve report performance with large data

Your Power BI report is slow because it uses a large sales dataset. Which approach will best improve report performance?

A Use live connection to Excel files stored locally

B Import the entire dataset and use many calculated columns

C Create many visuals with complex filters on the report page

D Use DirectQuery mode and avoid calculated columns where possible

💡 Hint

Consider how data is accessed and calculations are done.

DirectQuery mode queries the data source directly, reducing memory use. Avoiding calculated columns reduces processing load. Importing large data or many complex visuals slows performance.

🔧 Formula Fix

expert

Identify the error in this DAX measure

What error will this DAX measure produce?

Total Sales Last Year = CALCULATE(SUM(Sales[SalesAmount]), SAMEPERIODLASTYEAR(Sales[Date]))

Power BI

Total Sales Last Year = CALCULATE(SUM(Sales[SalesAmount]), SAMEPERIODLASTYEAR(Sales[Date]))

A Error: SAMEPERIODLASTYEAR requires a continuous date column marked as Date table

B SyntaxError: Missing parentheses in SAMEPERIODLASTYEAR function

C No error, measure returns total sales for last year correctly

D TypeError: SUM function cannot be used inside CALCULATE

💡 Hint

Check the requirements for time intelligence functions in Power BI.

SAMEPERIODLASTYEAR requires the date column to be from a properly marked Date table with continuous dates. Without this, it produces an error. The syntax is correct, and SUM can be used inside CALCULATE.