0 reads0 ratings0 helpful
If n(A) = 5, n(B) = 4, and n(A ∩ B) = 2, what is n(A ∪ B)?
Advertisement
Answer and explanation
Correct answer: 7
For two finite sets, the cardinality formula is n(A ∪ B) = n(A) + n(B) − n(A ∩ B). Adding n(A) and n(B) initially counts the two common elements twice, so their intersection must be subtracted once. Substitution gives 5 + 4 − 2 = 7. Hence n(A ∪ B) = 7, making option A correct.
Frequently asked questions
What is the correct answer to this question?
7
Why is this the correct answer?
For two finite sets, the cardinality formula is n(A ∪ B) = n(A) + n(B) − n(A ∩ B). Adding n(A) and n(B) initially counts the two common elements twice, so their intersection must be subtracted once. Substitution gives 5 + 4 − 2 = 7. Hence n(A ∪ B) = 7, making option A correct.
Which subject and chapter does this question cover?
This is a Class 12 Mathematics question. Chapter: Sets.
Student feedback
Was this question useful?
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Difficulty
Easy0%
Medium0%
Hard0%
Was the explanation clear?
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
Advertisement