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

If A ⊆ B, n(A) = 28, and n(B) = 73, what is n(B − A)?

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Answer and explanation

Correct answer: 45

Because A is a subset of B, every element of A is already included in B. The set B − A therefore contains the elements that belong to B but do not belong to A. No overlap is counted in this difference, so n(B − A) = n(B) − n(A) = 73 − 28 = 45. Thus, option B is correct.

Tags

setssubsetset differencecardinalityOperations on Sets (UnionIntersectionDifference)operations on sets union intersection differenceMathematicsClass 10 MCQ

Frequently asked questions

What is the correct answer to this question?

45

Why is this the correct answer?

Because A is a subset of B, every element of A is already included in B. The set B − A therefore contains the elements that belong to B but do not belong to A. No overlap is counted in this difference, so n(B − A) = n(B) − n(A) = 73 − 28 = 45. Thus, option B is correct.

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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