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

Given n(X) = 17, n(Y) = 23, n(X∪Y) = 38

But n(X∪Y) = n(X) + n(Y)-n(X∩Y)∩(X∩Y)

= 17 + 23-38 = 2