Question

If A,B,C are three events then prove that

P( ) () () A ∪ B = P A + P B − P( A ∩ B)​

Answer 1

n(A U B) =n(A-B) +n(B-A) + n(A ∩ B)        = n(A) - n(A∩ B) +n(B) -n(A∩ B) +n(A∩ B) =n(A)+n(B) -n(A∩ B)