SOLUTION: Use the addition principle for counting to solve the problem: If n(A)=20, n(A U B)=58, and n(A "intersection" B)=16, Find n(B)

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Question 631589: Use the addition principle for counting to solve the problem:
If n(A)=20, n(A U B)=58, and n(A "intersection" B)=16, Find n(B)

Answer by rapaljer(4671) About Me  (Show Source):
You can put this solution on YOUR website!
In order to get the UNION of two sets, you can ADD the number of members of the two sets together, and SUBTRACT the OVERLAP. The OVERLAP is actually the INTERSECTION. This gives the following formula:

n(A) + n(B)-n(A intersection B)=n(AUB)
20 + n(B) -16 = 58
4 + n(B) = 58
n(B) = 58-4 = 54

Dr. Robert J. Rapalje, Retired
Seminole State College of Florida