Question

Set A has 40 elements. Set B has 20 elements. The union of the two sets has 45 elements. How many elements are there in the intersection of A and B

Answer 1

A ∩ B = 15 elements

Explanation:

set A = 40 elements

set B = 20 elements

A ∪ B = 45 elements

total elements of both sets = 40 + 20 = 60

which means that, 60 - 45= 15 elements are common in both A and B and hence are written once for the union

thus, A ∩ B = 15 elements