In a Venn diagram, n(U) = 100, n(A) = 52, n(B) = 44, and n(A ∩ B) = 21. What is n((A ∪ B)ᶜ)?
Answer and explanation
Correct answer: 25
First find the number of elements in the union using inclusion–exclusion: n(A ∪ B) = n(A) + n(B) − n(A ∩ B) = 52 + 44 − 21 = 75. The complement contains all elements of the universal set that are not in the union. Hence n((A ∪ B)ᶜ) = n(U) − n(A ∪ B) = 100 − 75 = 25.
Frequently asked questions
What is the correct answer to this question?
25
Why is this the correct answer?
First find the number of elements in the union using inclusion–exclusion: n(A ∪ B) = n(A) + n(B) − n(A ∩ B) = 52 + 44 − 21 = 75. The complement contains all elements of the universal set that are not in the union. Hence n((A ∪ B)ᶜ) = n(U) − n(A ∪ B) = 100 − 75 = 25.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Complement of a Set and Its Properties.