If A △ B = (A \ B) ∪ (B \ A), |A △ B| = 34, and |A ∪ B| = 51, what is |A ∩ B|?
Answer and explanation
Correct answer: 17
The symmetric difference A △ B consists of the elements belonging to exactly one of the two sets. The union contains those elements together with the common elements in A ∩ B. Therefore |A ∪ B| = |A △ B| + |A ∩ B|. Substituting the values gives 51 = 34 + |A ∩ B|, so |A ∩ B| = 17.
Frequently asked questions
What is the correct answer to this question?
17
Why is this the correct answer?
The symmetric difference A △ B consists of the elements belonging to exactly one of the two sets. The union contains those elements together with the common elements in A ∩ B. Therefore |A ∪ B| = |A △ B| + |A ∩ B|. Substituting the values gives 51 = 34 + |A ∩ B|, so |A ∩ B| = 17.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).