A and B are the only two outcomes of an event.Probability of P(A)=0.72,then what will be the probability P(B) and why?

Given:

P(A)=0.72

As, we know that maximum probability for occurrence of  any event is 1.

∴ P(A) + P(B) = 1

⇒ 0.72 + P(B) = 1

⇒ P(B) = 1 - 0.72

⇒ P(B) = 0.28