Question Detail
Question
If \( n(A)=20 \), \( n(B)=15 \), \( n(A \cap B)=5 \), find \( n(A \cup B) \)?
Correct Answer
Option A is the correct answer.
Detailed Explanation
n(A ∪ B) = n(A) + n(B) - n(A ∩ B) = 20 + 15 - 5 = 30.
Hint
Use inclusion-exclusion: n(A ∪ B) = n(A) + n(B) - n(A ∩ B).