Question

If n(A) = 10, n(B) = 12 and n(AB) = 6, then find n(AB).

Answer 1

Answer

n(A∪B)=n(A)+n(B)−n(A∩B)−−−−−−−(1)

Given n(A)=7

n(B)=9

n(A∪B)=14

Substituting in 1

14=7+9−n(A∩B)

⇒n(A∩B)=16−14=2

Answer 2

Answer:

n(A∪B)=n(A)+n(B)-n(A∩B)

So we know n(A), n(B), n(A∩B) values are 10, 12, 6 respectively.

Therefore

n(A∪B)=10+12-6

Which is

n(A∪B)=16