Question

If X and Y are two sets such that n(X) = 17, n(Y) = 23 and n(X ∪ Y) = 38, find n(X ∩Y).

Answer 1

It is given that:

n(X) = 17, n(Y) = 23, n(X ∪ Y) = 38

n(X ∩ Y) = ?

We know that:

n(X ∩ Y)=n(X)+n(Y)-n(X ∪ Y)

38=17+23-n(X ∪ Y)

n(X ∪ Y)=40-38=2

∴ n(X ∪ Y)=2