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Let A and B be two sets such that n( A) = 20, n(A ∪ B) = 42, n(A ∩ B) = 4. Find1. n(B)2. n(B – A)3. n(A – B) |
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Answer» 1. n(A ∪ B) = n(A) + n(B) – n(A ∩ B) ⇒ 42 = 20 + n(B) – 4 ⇒ n(B) = 26 2. n(B – A) = n(B) – n(A ∩ B) = 26 – 4 = 22 3. n(A – B) = n(A) – n(A ∩ B) = 20 – 4 = 16. |
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