Question

1. Let A and B be two non-empty finite sets. If cardinalities of the sets A, B, and are respectively 72, 28 and 13, then find the cardinality of the set .

Answer 1

Given : n(A)=72,n(B)= 28 , and n(AnB)= 13

Solution : n(AUB)= n(A)+n(B)-n(AnB)

=72+28-13

= 87