Question: If set A contains 10 elements, set B contains 15 elements, and the intersection of A and B contains 5 elements, what is the number of elements in the union of sets A and B?
Options:
Correct Answer: 20
Solution:
The number of elements in the union of sets A and B is given by |A ∪ B| = |A| + |B| - |A ∩ B| = 10 + 15 - 5 = 20.