If n(A ∪ B ∪ C) = 95, exactly one set contains 46 elements, and exactly two sets contain 33 elements, what is n(A ∩ B ∩ C)?
Answer and explanation
Correct answer: 16
The union of three sets is divided into three mutually exclusive categories: elements in exactly one set, elements in exactly two sets, and elements in all three sets. Hence 95 = 46 + 33 + n(A ∩ B ∩ C). Solving gives n(A ∩ B ∩ C) = 95 − 79 = 16. The categories must be added once each because they do not overlap.
Frequently asked questions
What is the correct answer to this question?
16
Why is this the correct answer?
The union of three sets is divided into three mutually exclusive categories: elements in exactly one set, elements in exactly two sets, and elements in all three sets. Hence 95 = 46 + 33 + n(A ∩ B ∩ C). Solving gives n(A ∩ B ∩ C) = 95 − 79 = 16. The categories must be added once each because they do not overlap.
Which subject and chapter does this question cover?
This is a Class 12 Mathematics question. Chapter: Sets.
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