SOLUTION: If n(A∪B)=60 , n(A∩B)=20, and n(A)=n(B), find n(A) A. 10 B. 30 C. 40 D. 20

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Question 1060722: If n(A∪B)=60 , n(A∩B)=20, and n(A)=n(B), find n(A)
A. 10
B. 30
C. 40
D. 20
Answer by ikleyn(52794) About Me  (Show Source):
You can put this solution on YOUR website!
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It is clear and widely well known that n(A U B) = n(A) + n(B) - n(A n B).

For the given case, it implies that 60 = 2*n(A) - 20, or

n(A) = 40.

Solved.