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Class 10MathematicsSetsOperations on Sets (Union, Intersection, Difference)EasyLevel 10

If A ∩ B = ∅, n(A) = 15, and n(B) = 18, what is n(A ∪ B)?

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Answer and explanation

Correct answer: 33

The symbol ∅ means that A and B are disjoint, so their intersection has zero elements. The union formula is n(A ∪ B) = n(A) + n(B) − n(A ∩ B). Substituting the values gives 15 + 18 − 0 = 33. Since no element is counted in both sets, the two cardinalities can be added directly.

Tags

setsdisjoint-setsunioncardinalityOperations on Sets (UnionIntersectionDifference)operations on sets union intersection differenceMathematicsClass 10 MCQ

Frequently asked questions

What is the correct answer to this question?

33

Why is this the correct answer?

The symbol ∅ means that A and B are disjoint, so their intersection has zero elements. The union formula is n(A ∪ B) = n(A) + n(B) − n(A ∩ B). Substituting the values gives 15 + 18 − 0 = 33. Since no element is counted in both sets, the two cardinalities can be added directly.

Which subject and chapter does this question cover?

This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).

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