PL-300 Practice Test 2 — 10 Questions

Question 1

You need to create a calculated column in Power BI that shows the full name by combining 'FirstName' and 'LastName' columns with a space. Which DAX expression should you use?

Accepted Answer

FullName = [FirstName] & " " & [LastName]. The DAX concatenation operator is the ampersand (&). Option B is wrong because CONCATENATE function only takes two arguments. Option C is wrong because CONCATENATEX is for tables. Option D is wrong because the plus sign is for addition.

Answer

FullName = CONCATENATE([FirstName], " ", [LastName])

Answer

FullName = CONCATENATEX(Table, [FirstName] & " " & [LastName])

Answer

FullName = [FirstName] + " " + [LastName]

Question 2

You have a Power BI dataset that uses data from Microsoft Excel files stored in SharePoint Online. Users report that the data is not refreshing as scheduled. You verify that the gateway is installed and running. What is the most likely cause of the refresh failure?

Accepted Answer

The data source credentials are not provided in the gateway.. Even when the gateway is installed and running, it must have valid data source credentials configured for the SharePoint Online Excel files. Without these credentials, the gateway cannot authenticate to SharePoint Online to retrieve the data, causing the scheduled refresh to fail. The gateway uses the stored credentials to connect to the data source during each refresh cycle.

Answer

The gateway is not running.

Answer

The gateway does not support SharePoint Online data sources.

Answer

The gateway is not configured to use the on-premises data source type.

Question 3

A Power BI data model includes a table 'Orders' with columns OrderID, CustomerID, OrderDate, SalesAmount. The model also has a 'Date' table and a 'Customer' table. The relationships are: Orders[CustomerID] -> Customer[CustomerID] (many-to-one, single direction) and Orders[OrderDate] -> Date[Date] (many-to-one, single direction). A user creates a measure that sums SalesAmount and then filters by a slicer on Customer[City]. The slicer works correctly. However, when the user adds another slicer on Date[Year], the measure does not respect both slicers simultaneously. What is the most likely cause?

Accepted Answer

The measure might be using ALL or ALLEXCEPT that removes the filter context from the Date table.. The measure likely uses ALL or ALLEXCEPT, which removes the filter context from the Date table. Even though the relationships are correctly configured and filters from the Date slicer propagate to Orders via the single-direction relationship, if the measure explicitly ignores those filters using a function like ALL(Date[Year]) or ALLEXCEPT(Orders, ...), the Date slicer will have no effect on the measure. This is a common DAX mistake where filter removal functions override slicer selections.

Answer

The Customer and Date tables are not related to each other.

Answer

The relationship between Orders and Date is inactive.

Answer

The relationships are set to single direction, so filters from Date do not propagate to Orders.

Question 4

You have the above M query. You need to load only the top 10 customers by sales. What should you add to the query?

Accepted Answer

Add Table.FirstN(#"Sorted Rows", 10) after sorting.. The query already sorts by Total Sales descending. To get top 10, you need to add a step to keep the first 10 rows, using Table.FirstN.

Answer

Add a step to use Table.SelectRows with a condition on rank.

Answer

Add a filter to keep only rows where [Total Sales] is in the top 10 values.

Answer

Add a step to use Table.StopAfter(#"Sorted Rows", 10).

Question 5

You are troubleshooting a Power Query transformation that groups sales data by ProductID. The query runs slowly and you suspect the filter is being applied after loading all rows. What change would improve performance by pushing the filter to the source?

Accepted Answer

Replace the first three lines with a native SQL query that includes the WHERE clause. Pushing filter logic to the source database via a native SQL query with a WHERE clause reduces the amount of data loaded into Power Query. This leverages query folding, which allows the source (e.g., SQL Server) to perform the filtering before data is transferred, significantly improving performance for large datasets.

Answer

Disable the 'Enable load' option for the SalesTable

Answer

Use CALCULATE in DAX to filter

Answer

Add a 'Table.Buffer' step after the filter

Question 6

You are a Power BI data analyst at a university. You import a table named Enrollments from an on-premises SQL Server database. The table contains a column named StudentEmail that is stored as text and sometimes has leading or trailing spaces. You need to remove these spaces so that the column can be used to create a relationship with a Students table that also has a StudentEmail column. You must perform this cleanup in Power Query, and the transformation must apply to the entire column without creating a new column. Which transformation should you use?

Accepted Answer

On the Transform tab, select Format and then Trim.. Trim is the Power Query transformation that removes leading and trailing whitespace from text values in place. Applying it from the Transform tab modifies the existing StudentEmail column, so the cleaned values can match the Students table and support the relationship. The Add Column variant would create a separate column, and Clean or Replace Values do not correctly remove only the surrounding spaces.

Answer

On the Add Column tab, select Format and then Trim.

Answer

On the Transform tab, select Replace Values and replace a space with an empty value.

Answer

On the Transform tab, select Format and then Clean.

Question 7

You are connecting to a SharePoint folder containing 100 Excel files. Each file has a similar structure but different column names. What is the best practice to combine these files into a single table while preserving the data?

Accepted Answer

Use Power Query's 'Combine Files' feature, selecting a sample file and promoting headers, then transforming column names to a standard set.. Power Query's 'Combine Files' feature is designed specifically for this scenario: it uses a sample file to infer the transformation logic (e.g., promoting headers), then applies that logic to all files in the folder. By transforming column names to a standard set within the sample file step, you ensure consistent column names across all files, preserving data integrity while combining them into a single table.

Answer

Load each file as a separate table and create relationships in the model.

Answer

Use Power Query's 'Merge Queries' to join all files into one table.

Answer

Use 'Append Queries' to stack all files, then rename columns manually.

Question 8

You are designing a report for executives. The report contains a matrix visual with many rows and columns. Users complain that the visual is slow to render. Which design change would most improve performance?

Accepted Answer

Use a drill-down hierarchy instead of expanding all levels.. Aggregating data at a higher level reduces the number of data points, improving performance. Drilling down can still provide detail when needed.

Answer

Switch to a table visual.

Answer

Add more filters to the visual.

Answer

Increase the number of measures in the matrix.

Question 9

A company wants to create a Power BI report that shows sales performance by region. The data contains a table 'Sales' with columns: Date, Amount, RegionID, and ProductID. They also have a 'Regions' table with RegionID and RegionName. They want to display a matrix visual with RegionName on rows and Year on columns, with the sum of Amount as values. However, the report displays only 'RegionID' instead of 'RegionName'. What is the most likely cause?

Accepted Answer

There is no active relationship between the Sales and Regions tables.. If there is no active relationship between the Sales and Regions tables, Power BI cannot use the RegionName from the Regions table to filter or group the Sales data. Instead, it defaults to displaying the RegionID from the Sales table, which is the only related field available in the visual. An active relationship must exist between the two tables on the RegionID columns for RegionName to appear in the matrix.

Answer

The relationship is configured as many-to-many.

Answer

The relationship direction is set to Both.

Answer

The RegionID column in the Sales table is hidden.

Question 10

You need to create a visualization that shows the contribution of each product category to total sales over time. Which chart type is most appropriate?

Accepted Answer

Stacked area chart. A stacked area chart is correct because it plots each product category as a cumulative band over a continuous time axis, so the total height shows overall sales while each band's thickness shows that category's contribution to the total at every point in time. This directly satisfies the requirement to show both contribution by category and the trend over time. A clustered bar chart compares discrete category values side by side but does not naturally show their combined contribution to a running total over time. A scatter plot shows relationships between two numeric variables, not compositional contribution over time. A pie chart shows parts of a whole for a single point in time and cannot represent change over time.

Answer

Clustered bar chart

Answer

Scatter plot

Answer

Pie chart