11. In a library ER model, a book can have multiple authors. How should "authors" be represented?

A. Simple attribute
B. Multivalued attribute
C. Weak entity
D. Derived attribute

Answer: B
Explanation:

Since a book can have more than one author, "authors" should be modeled as a multivalued attribute or as a separate related entity in logical design.

12. A bank wants to model that each customer may have multiple accounts, and each account may belong to multiple customers (joint accounts). How should this be modeled?

A. One-to-one relationship
B. One-to-many relationship
C. Many-to-many relationship
D. Recursive relationship

Answer: C
Explanation:

This is a many-to-many relationship between Customer and Account. An associative entity may be used to store additional attributes like account balance or ownership percentage.

13. In a hospital, lab test results depend on both the patient and the test type. How should this relationship be represented?

A. Simple relationship
B. Associative entity
C. Weak entity
D. Derived attribute

Answer: B
Explanation:

The result is an attribute of the relationship between Patient and Test. This requires an associative entity to store attributes like test date and result value.

14. In a university, a course can have multiple sections, and a section must belong to one course. How is “Section” classified?

A. Strong entity
B. Weak entity
C. Multivalued attribute
D. Derived attribute

Answer: B
Explanation:

“Section” depends on “Course” for identification and cannot exist independently, making it a weak entity.

15. In an e-commerce system, an order can contain multiple products, each with quantity and price. How should this be modeled?

A. Add attributes to Order
B. Add attributes to Product
C. Use an associative entity Order_Product
D. Use derived attributes

Answer: C
Explanation:

Since quantity and price depend on the combination of Order and Product, an associative entity is required to store these relationship attributes.

16. In a company, an employee can supervise multiple employees, but an employee can have only one supervisor. What type of relationship is this?

A. One-to-one
B. One-to-many recursive
C. Many-to-many
D. Weak entity

Answer: B
Explanation:

This is a recursive one-to-many relationship where an Employee entity relates to itself as supervisor and subordinate.

17. In a hospital, a prescription is issued by a doctor to a patient. Each prescription includes multiple medicines. How should medicines be represented?

A. Multivalued attribute
B. Weak entity
C. Derived attribute
D. Recursive relationship

Answer: B
Explanation:

Medicines are modeled as a weak entity related to the prescription entity, since their details exist in the context of a specific prescription.

18. In a travel booking system, a passenger may book multiple trips, and a trip may include multiple passengers. How should this relationship be represented?

A. One-to-one
B. One-to-many
C. Many-to-many
D. Recursive

Answer: C
Explanation:

This is a many-to-many relationship, often implemented via an associative entity (e.g., Booking) to store additional attributes like booking date.

19. A student can be both a class representative and a club president. How would this specialization be represented?

A. Disjoint specialization
B. Overlapping specialization
C. Total specialization
D. Partial specialization

Answer: B
Explanation:

Overlapping specialization allows an entity to belong to multiple subtypes simultaneously.

20. In a university ER model, "GPA" is computed from grades. How should GPA be represented?

A. Simple attribute
B. Derived attribute
C. Multivalued attribute
D. Weak entity

Answer: B
Explanation:

GPA is a derived attribute because it can be calculated from the grades of the student in various courses.