CMA Foundation · Fundamentals of Business Mathematics and Statistics · Set Theory, including Venn Diagram
If n(U) = 200, n(A) = 90, n(B) = 70 and n(A ∪ B) = 130, find n(A' ∪ B').
The correct value is 170, obtained as 200 minus the intersection of 30, but this is not among the options.
- A130
- B160Correct
- C200
- D70
Explanation
n(A ∩ B) = 90 + 70 − 130 = 30. By De Morgan, A' ∪ B' = (A ∩ B)', so n = 200 − 30 = 170. Check: none of the options equals 170, so the key is flawed.
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