two sets are formed using 100 elements. there are 69 elements in one set and 74 in the other. how many elements are in the intersection of the two sets

Question

 i need helping finding out how to do this answer 

Answer 1

N(AUB)=N(A)+N(B)-N(A∩B) my notation here is N(A)=the number of elements in the set A and so on.

 

We know that: N(A)=69

                      N(B)=74 

and                 N(AUB)=100

so we can solve for the number in the intersection i.e. N(A∩B)=N(A)+N(B)-N(AUB)

N(A∩B)=143-100=43

 

Hope this helps

 

Jim