Microsoft Power BI Data Analyst
Associate Study Guide: Prepare for
the PL-300 Exam and Use Power BI
Successfully 1st Edition
SECTION 1: PREPARE THE DATA
Question 1
Which scenario would justify using the Import storage mode over DirectQuery?
A) When you need to query a 20 TB SQL Server table with millions of rows
B) When you have a small, static dataset that requires frequent use in reports
C) When you need to display real-time stock market data that changes every second
D) When you need to establish live connectivity to an Analysis Services cube
Correct Answer: B
Rationale: Import mode is recommended for small or static datasets where you want to
deliver the best performance for reporting. Since the data is copied into Power BI's in-
memory VertiPaq engine, refresh schedules are acceptable and query performance is fast.
DirectQuery is better suited for large datasets or near-real-time requirements.
,Question 2
Which Power Query tool should be used to replace NULL values in a specific
column with a default value like "0"?
A) Replace Errors
B) Fill Down
C) Replace Values
D) Pivot Column
Correct Answer: C
Rationale: The "Replace Values" operation in Power Query is used to substitute specific
values, including NULL, with another value. It can replace a target value (e.g., null, "N/A",
or a specific string) with a default value like "0".
Question 3
What is the primary advantage of performing data transformations in the source
SQL query rather than in Power Query?
A) It reduces the number of tables in the model
B) It makes the M code easier to read
C) It results in faster performance due to query folding
D) It automatically creates relationships
Correct Answer: C
Rationale: Pushing transformations like filtering and grouping to the source database by
writing efficient SQL leverages the source's processing power. This practice, known as
query folding, reduces the amount of data loaded into Power BI and typically results in
much faster overall performance.
Question 4
, Which storage mode should be used to combine data from multiple sources
without importing all data into Power BI?
A) Import
B) DirectQuery
C) Composite
D) Live Connection
Correct Answer: C
Rationale: A Composite model uses both Import and DirectQuery modes in a single model.
This allows combining data from multiple sources—some data can be imported for
performance while other data remains in DirectQuery for real-time needs—without
importing all of it.
Question 5
You have a table with a "Date" column containing dates from 2020 to 2025, a
"ProductID" column, and a "Sales" column. You need to unpivot the data so that
"ProductID" and "Sales" become attribute-value pairs. What is the first step?
A) Group By
B) Select the columns to unpivot
C) Merge Queries
D) Change the Date column data type
Correct Answer: B
Rationale: To unpivot in Power Query, you first select the columns you want to transform
into rows (the value columns). Then go to the 'Transform' tab and click 'Unpivot Columns'.
This operation turns columns into attribute-value pairs.
Question 6
Associate Study Guide: Prepare for
the PL-300 Exam and Use Power BI
Successfully 1st Edition
SECTION 1: PREPARE THE DATA
Question 1
Which scenario would justify using the Import storage mode over DirectQuery?
A) When you need to query a 20 TB SQL Server table with millions of rows
B) When you have a small, static dataset that requires frequent use in reports
C) When you need to display real-time stock market data that changes every second
D) When you need to establish live connectivity to an Analysis Services cube
Correct Answer: B
Rationale: Import mode is recommended for small or static datasets where you want to
deliver the best performance for reporting. Since the data is copied into Power BI's in-
memory VertiPaq engine, refresh schedules are acceptable and query performance is fast.
DirectQuery is better suited for large datasets or near-real-time requirements.
,Question 2
Which Power Query tool should be used to replace NULL values in a specific
column with a default value like "0"?
A) Replace Errors
B) Fill Down
C) Replace Values
D) Pivot Column
Correct Answer: C
Rationale: The "Replace Values" operation in Power Query is used to substitute specific
values, including NULL, with another value. It can replace a target value (e.g., null, "N/A",
or a specific string) with a default value like "0".
Question 3
What is the primary advantage of performing data transformations in the source
SQL query rather than in Power Query?
A) It reduces the number of tables in the model
B) It makes the M code easier to read
C) It results in faster performance due to query folding
D) It automatically creates relationships
Correct Answer: C
Rationale: Pushing transformations like filtering and grouping to the source database by
writing efficient SQL leverages the source's processing power. This practice, known as
query folding, reduces the amount of data loaded into Power BI and typically results in
much faster overall performance.
Question 4
, Which storage mode should be used to combine data from multiple sources
without importing all data into Power BI?
A) Import
B) DirectQuery
C) Composite
D) Live Connection
Correct Answer: C
Rationale: A Composite model uses both Import and DirectQuery modes in a single model.
This allows combining data from multiple sources—some data can be imported for
performance while other data remains in DirectQuery for real-time needs—without
importing all of it.
Question 5
You have a table with a "Date" column containing dates from 2020 to 2025, a
"ProductID" column, and a "Sales" column. You need to unpivot the data so that
"ProductID" and "Sales" become attribute-value pairs. What is the first step?
A) Group By
B) Select the columns to unpivot
C) Merge Queries
D) Change the Date column data type
Correct Answer: B
Rationale: To unpivot in Power Query, you first select the columns you want to transform
into rows (the value columns). Then go to the 'Transform' tab and click 'Unpivot Columns'.
This operation turns columns into attribute-value pairs.
Question 6
