Question

if n(A) = 11; n(B) = 7; n(A∪B) = 13 then find n(A∩B).


5

6

7

2​

Answer 1

n(A) = 11; n(B) = 7; n(A∪B) = 13 n(A∩B).=?

we know that,n(A∪B)=n(A)+ n(B)-n(A∩B)

or,13=11+7-n(A∩B)

or,13-18= -n(A∩B)

hence n(A∩B)=5