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If P and Q are finite sets where n(Q) = 90 and n(P⋂Q) = 30 , n(P⋃Q) = 108 find n(P-Q): |
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Answer» we have a formula N(PUQ) = n(P) + n(Q) - n(P⋂Q) from that we get 108 = x + 90 - 30 108 + 30 = x + 90 138 - 90 = x x = 48 therefore n(P) = 48 we have another formula n(P-Q) = n(P) - n(P⋂Q) from that n(P-Q) = 48 - 30 n(P-Q) = 18 THEREFORE n(P-Q) = 18 |
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