Question

If n(a)=40,n(b)=60 and n(a∪b)=80.find the value of (a∩b.

Answer 1

20

Explanation:

we know,

n(aUb)=n(a)+n(b)-n(a∩b)

so,

80=40+60-n(a∩b)

or, 80-(40+60)=-n(a∩b)

or, -n(a∩b)=80-100

or, -n(a∩b)=-20

or, n(a∩b)=20