Use the union rule to answer if nA 9 nB 11 and nA intersec

Use the union rule to answer. if n(A) = 9, n(B) = 11 and n(A intersection B) =6, what is n(A union B)? N(A union B) =

Solution :

Given : n(A) = 9, n(B) = 11 and n(AB) = 6

Find : n(A U B)

We know that,

n(A U B) = n(A) + n(B) - n(A B)

n(A U B) = 9 + 11 - 6

n(A U B) = 20 - 6

n(A U B) = 14

Hence, n(A U B) = 14