Question

If n(A) = 7, n(B) = 13, n(A ∩ B) = 4, then n(A ∪ B) =?

Answer 1

We have, 

n(A) = 7, n(B) = 13 and n(A ∩ B) = 4

Since, n(A ∪ B) = n(A) + n(B) - n(A ∩ B)

= 7 + 13 - 4

∴ n(A ∪ B) = 16