Question

If A anf B are tow disjoint sets and n(A)=10 and n(B)=8find n (AUB)and n(AnB)

Answer 1

A and B are disjoint sets so they don't have any elements common.

So,

n(A ∪ B) = n(A) + n(B)

==> n(A ∪ B) = 10 + 8

==> n(A ∪ B) = 18

Also,

==> n(A ⋂ B) = 0 ( because the sets are disjoint )