This post is a part of the PL-300: Microsoft Power BI Data Analyst Exam Prep Hub; and this topic falls under these sections:
Model the data (25–30%)
   --> Design and implement a data model
      --> Define a Relationship's Cardinality and Cross-Filter Direction

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.

---

Practice Questions

---

Question 1

You are designing a star schema with a Sales fact table and a Product dimension table. Which relationship configuration is recommended?

A. Many-to-many with bi-directional filtering
B. One-to-many with single-direction filtering
C. One-to-one with single-direction filtering
D. Many-to-one with bi-directional filtering

✅ Correct Answer: B

Explanation:
A star schema should use a one-to-many relationship from the dimension (Product) to the fact (Sales) with single-direction filtering for predictable results and optimal performance.

---

Question 2

When should bi-directional cross-filtering be used?

A. In all relationships by default
B. Only for dimension-to-dimension relationships
C. When complex filtering across tables is required
D. Only in one-to-many relationships

✅ Correct Answer: C

Explanation:
Bi-directional filtering should be used only when necessary, such as in many-to-many or fact-to-fact scenarios, because it can introduce ambiguity and performance issues.

---

Question 3

What is the most common cause of a many-to-many relationship?

A. Missing primary keys
B. Duplicate values on both sides of the relationship
C. Using calculated columns
D. Incorrect data types

✅ Correct Answer: B

Explanation:
Many-to-many relationships occur when both tables contain duplicate values in the join column.

---

Question 4

A dimension table contains duplicate keys. What is the best solution?

A. Enable bi-directional filtering
B. Change the relationship to many-to-many
C. Remove duplicates or create a bridge table
D. Ignore the issue

✅ Correct Answer: C

Explanation:
Dimension tables should contain unique keys. Removing duplicates or introducing a bridge table preserves correct aggregation behavior.

---

Question 5

Which cross-filter direction prevents a fact table from filtering a dimension table?

A. Both
B. None
C. Single
D. Auto

✅ Correct Answer: C

Explanation:
Single-direction filtering allows filters to flow from the one-side (dimension) to the many-side (fact) only.

---

Question 6

What is a risk of using bi-directional relationships excessively?

A. Reduced model size
B. Automatic time intelligence
C. Circular dependencies and ambiguous filters
D. Improved query performance

✅ Correct Answer: C

Explanation:
Bi-directional filtering can create ambiguous filter paths, circular dependencies, and incorrect results if overused.

---

Question 7

You have two fact tables that must be analyzed together. What relationship design is most appropriate?

A. One-to-many with single direction
B. Many-to-many with bi-directional filtering
C. One-to-one with single direction
D. No relationship

✅ Correct Answer: B

Explanation:
Fact-to-fact analysis typically requires many-to-many relationships with bi-directional filtering, often via a bridge table.

---

Question 8

Why are one-to-one relationships uncommon in Power BI models?

A. They are not supported
B. They cause performance issues
C. Tables can often be merged instead
D. They require bi-directional filtering

✅ Correct Answer: C

Explanation:
One-to-one relationships often indicate the tables could be merged, simplifying the model.

---

Question 9

What is the default cross-filter direction for a one-to-many relationship in Power BI?

A. Both
B. Single
C. None
D. Auto

✅ Correct Answer: B

Explanation:
Power BI defaults to single-direction filtering from the one-side to the many-side.

---

Question 10

A report returns inflated totals after enabling bi-directional filtering. What is the most likely cause?

A. Incorrect data types
B. Duplicate measures
C. Ambiguous filter propagation
D. Missing relationships

✅ Correct Answer: C

Explanation:
Bi-directional filtering can cause filters to propagate through multiple paths, leading to double-counting or inflated results.

---

Key Exam Reminders 🧠

• Default to one-to-many + single direction
• Use bi-directional filtering sparingly
• Watch for duplicate keys
• Many-to-many ≠ shortcut
• Think in terms of filter flow, not just connectivity

---

Go back to the PL-300 Exam Prep Hub main page