WGU C170 PRE-ASSESSMENT FJO1 PFJO 2026/2027 | Data
Management Applications | Complete Solution | Pass
Guaranteed - A+ Graded
Section 1: Database Fundamentals & Relational Model (Questions
1-12)
Q1. A database administrator is explaining the relational model to a new hire. She
states: "In a relation, each column represents a specific characteristic, and each row
represents a single instance." Which two terms correctly identify what columns and
rows represent in formal relational terminology?
A. Columns represent records, and rows represent fields.
B. Columns represent attributes, and rows represent tuples.
C. Columns represent domains, and rows represent degrees.
D. Columns represent schemas, and rows represent instances.
Rationale: In the formal relational model, columns are called attributes (characteristics),
and rows are called tuples (individual records/instances). Option A reverses the terms.
Option C confuses domain (set of valid values for an attribute) and degree (number of
attributes in a relation). Option D uses schema and instance at the database level, not
the relation level.
Correct Answer: B
,Q2. A university registrar maintains a STUDENT relation with 15,000 rows and 8
columns. Which pair of terms correctly describes the degree and cardinality of this
relation?
A. Degree: 15,000; Cardinality: 8
B. Degree: 8; Cardinality: 15,000
C. Degree: 120,000; Cardinality: 8
D. Degree: 15,000; Cardinality: 120,000
Rationale: Degree refers to the number of attributes (columns) in a relation, which is 8.
Cardinality refers to the number of tuples (rows), which is 15,000. Options A and D
reverse these definitions. Option C incorrectly multiplies the values.
Correct Answer: B
Q3. A database designer is defining a CUSTOMER relation. The PhoneNumber attribute
should only accept valid 10-digit North American phone numbers. What relational
concept describes the set of permissible values for the PhoneNumber attribute?
A. Tuple
B. Domain
C. Schema
D. Cardinality
,Rationale: A domain is the set of all permissible values for a given attribute. A tuple is a
row (Option A). A schema is the overall structure of the database (Option C). Cardinality
is the number of rows (Option D).
Correct Answer: B
Q4. Which relational algebra operation produces a vertical subset of a relation by
selecting specific columns while eliminating duplicate rows?
A. Selection (σ)
B. Projection (π)
C. Union (∪)
D. Intersection (∩)
Rationale: Projection (π) selects specific columns (attributes) from a relation, producing
a vertical subset. Selection (σ) produces a horizontal subset by filtering rows (Option A).
Union and Intersection are set operations combining relations (Options C and D).
Correct Answer: B
Q5. Consider two relations: EMPLOYEE(empID, name, deptID) and DEPARTMENT(deptID,
deptName, location). Which relational algebra expression returns only the names and
department names of employees who work in the "Marketing" department?
A. σ_deptName='Marketing' (EMPLOYEE × DEPARTMENT)
B. π_name, deptName (σ_deptName='Marketing' (EMPLOYEE ⋈ DEPARTMENT))
C. π_name, deptName (EMPLOYEE) ∪ π_deptName (DEPARTMENT)
, D. σ_name, deptName (EMPLOYEE ⋈ DEPARTMENT)
Rationale: The correct sequence is: (1) Join the relations on deptID, (2) Select rows
where deptName = 'Marketing', (3) Project only name and deptName columns. Option A
projects nothing and returns all columns. Option C uses Union incorrectly on
incompatible attributes. Option D misuses selection syntax (selection uses conditions,
not column lists).
Correct Answer: B
Q6. A database analyst needs to identify all customers who have placed an order AND
are also listed in the VIP_CUSTOMER relation. Which relational algebra operation is
most appropriate?
A. Union
B. Difference
C. Intersection
D. Cartesian Product
Rationale: Intersection (∩) returns only tuples that appear in both relations, identifying
customers present in both ORDER and VIP_CUSTOMER. Union would return all
customers from either relation (Option A). Difference would return customers in one but
not the other (Option B). Cartesian Product would combine all rows from both relations
(Option D).
Correct Answer: C
Management Applications | Complete Solution | Pass
Guaranteed - A+ Graded
Section 1: Database Fundamentals & Relational Model (Questions
1-12)
Q1. A database administrator is explaining the relational model to a new hire. She
states: "In a relation, each column represents a specific characteristic, and each row
represents a single instance." Which two terms correctly identify what columns and
rows represent in formal relational terminology?
A. Columns represent records, and rows represent fields.
B. Columns represent attributes, and rows represent tuples.
C. Columns represent domains, and rows represent degrees.
D. Columns represent schemas, and rows represent instances.
Rationale: In the formal relational model, columns are called attributes (characteristics),
and rows are called tuples (individual records/instances). Option A reverses the terms.
Option C confuses domain (set of valid values for an attribute) and degree (number of
attributes in a relation). Option D uses schema and instance at the database level, not
the relation level.
Correct Answer: B
,Q2. A university registrar maintains a STUDENT relation with 15,000 rows and 8
columns. Which pair of terms correctly describes the degree and cardinality of this
relation?
A. Degree: 15,000; Cardinality: 8
B. Degree: 8; Cardinality: 15,000
C. Degree: 120,000; Cardinality: 8
D. Degree: 15,000; Cardinality: 120,000
Rationale: Degree refers to the number of attributes (columns) in a relation, which is 8.
Cardinality refers to the number of tuples (rows), which is 15,000. Options A and D
reverse these definitions. Option C incorrectly multiplies the values.
Correct Answer: B
Q3. A database designer is defining a CUSTOMER relation. The PhoneNumber attribute
should only accept valid 10-digit North American phone numbers. What relational
concept describes the set of permissible values for the PhoneNumber attribute?
A. Tuple
B. Domain
C. Schema
D. Cardinality
,Rationale: A domain is the set of all permissible values for a given attribute. A tuple is a
row (Option A). A schema is the overall structure of the database (Option C). Cardinality
is the number of rows (Option D).
Correct Answer: B
Q4. Which relational algebra operation produces a vertical subset of a relation by
selecting specific columns while eliminating duplicate rows?
A. Selection (σ)
B. Projection (π)
C. Union (∪)
D. Intersection (∩)
Rationale: Projection (π) selects specific columns (attributes) from a relation, producing
a vertical subset. Selection (σ) produces a horizontal subset by filtering rows (Option A).
Union and Intersection are set operations combining relations (Options C and D).
Correct Answer: B
Q5. Consider two relations: EMPLOYEE(empID, name, deptID) and DEPARTMENT(deptID,
deptName, location). Which relational algebra expression returns only the names and
department names of employees who work in the "Marketing" department?
A. σ_deptName='Marketing' (EMPLOYEE × DEPARTMENT)
B. π_name, deptName (σ_deptName='Marketing' (EMPLOYEE ⋈ DEPARTMENT))
C. π_name, deptName (EMPLOYEE) ∪ π_deptName (DEPARTMENT)
, D. σ_name, deptName (EMPLOYEE ⋈ DEPARTMENT)
Rationale: The correct sequence is: (1) Join the relations on deptID, (2) Select rows
where deptName = 'Marketing', (3) Project only name and deptName columns. Option A
projects nothing and returns all columns. Option C uses Union incorrectly on
incompatible attributes. Option D misuses selection syntax (selection uses conditions,
not column lists).
Correct Answer: B
Q6. A database analyst needs to identify all customers who have placed an order AND
are also listed in the VIP_CUSTOMER relation. Which relational algebra operation is
most appropriate?
A. Union
B. Difference
C. Intersection
D. Cartesian Product
Rationale: Intersection (∩) returns only tuples that appear in both relations, identifying
customers present in both ORDER and VIP_CUSTOMER. Union would return all
customers from either relation (Option A). Difference would return customers in one but
not the other (Option B). Cartesian Product would combine all rows from both relations
(Option D).
Correct Answer: C
