Answer: 7.
- A 7
- B 9
- C 11
- D 6
Correct answer: A. 7
Explanation: n(A union B) = n(A) + n(B) - n(A intersect B) = 5 + 4 - 2 = 7.
A Venn diagram makes set identities visual: A∪B is everything inside either circle, A∩B is only the overlap, and the region outside both circles represents the complement of their union - directly illustrating De Morgan's law (A∪B)′ = A′∩B′.
Concept context
Types of sets, operations (union/intersection/complement), relations, and types of functions with domain and range