This post is a part of the PL-300: Microsoft Power BI Data Analyst Exam Prep Hub; and this topic falls under these sections:
Visualize and analyze the data (25–30%)
   --> Identify patterns and trends
      --> Use Reference Lines, Error Bars, and Forecasting

Below are 10 practice questions (with answers and explanations) for this topic of the exam.
There are also 2 practice tests for the PL-300 exam with 60 questions each (with answers) available on the hub.

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Practice Questions

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Question 1

A sales manager wants to see how monthly sales compare against a fixed revenue target on a line chart. What feature should you use?

A. Forecast
B. Error bars
C. Constant reference line
D. Decomposition Tree

Correct Answer: C

Explanation:
A constant reference line allows you to display a fixed benchmark, such as a sales target, across a visual.

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Question 2

Which pane in Power BI Desktop is used to add reference lines, error bars, and forecasting to a visual?

A. Fields pane
B. Visualizations pane
C. Filters pane
D. Analytics pane

Correct Answer: D

Explanation:
All three features—reference lines, error bars, and forecasting—are configured in the Analytics pane.

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Question 3

You want to show how much variation exists around average daily production values. Which feature is most appropriate?

A. Forecast
B. Error bars
C. Average line
D. Percentile line

Correct Answer: B

Explanation:
Error bars visualize variability or uncertainty, making them ideal for showing ranges around a value.

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Question 4

Which type of reference line dynamically adjusts based on the data displayed in the visual?

A. Constant line
B. Target line
C. Average line
D. Fixed percentile

Correct Answer: C

Explanation:
An average line recalculates automatically based on the values currently shown in the visual.

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Question 5

What is a requirement for using forecasting in Power BI?

A. The dataset must use DirectQuery
B. The visual must be a line chart with a continuous date axis
C. A calculated column must exist
D. The data must be categorical

Correct Answer: B

Explanation:
Forecasting requires a line chart and a continuous time-based axis, such as a date or datetime field.

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Question 6

Which statement about forecasting in Power BI is true?

A. Forecasting creates new measures
B. Forecasting permanently modifies the dataset
C. Forecasting uses historical trends to predict future values
D. Forecasting works on all visual types

Correct Answer: C

Explanation:
Power BI forecasting applies time-series analysis to historical data to project future values.

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Question 7

A report needs to show whether performance values fall above or below the median. Which reference line should you use?

A. Constant line
B. Percentile line
C. Median line
D. Forecast line

Correct Answer: C

Explanation:
A median line highlights the midpoint of the data and helps compare values above or below it.

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Question 8

Which scenario best justifies the use of error bars?

A. Comparing values to a fixed target
B. Explaining why a metric changed
C. Showing uncertainty or confidence ranges
D. Predicting future outcomes

Correct Answer: C

Explanation:
Error bars are used to represent uncertainty, variability, or confidence intervals, not targets or predictions.

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Question 9

Which limitation applies to Power BI forecasting?

A. It requires manual DAX calculations
B. It does not support confidence intervals
C. It cannot account for external factors not present in historical data
D. It only works in Power BI Service

Correct Answer: C

Explanation:
Forecasting relies entirely on historical patterns, so it cannot consider external events unless they are reflected in the data.

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Question 10

Which combination of features would best support analyzing trends, performance benchmarks, and uncertainty in a single visual?

A. Forecasting only
B. Error bars only
C. Reference line and forecast
D. Reference lines, error bars, and forecasting

Correct Answer: D

Explanation:
Using all three together allows you to show benchmarks (reference lines), variability (error bars), and future projections (forecasting).

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PL-300 Exam Tips

• Reference lines → benchmarks, averages, targets
• Error bars → variability and uncertainty
• Forecasting → time-series predictions
• All are configured in the Analytics pane
• None of these features modify the underlying data

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