For events \(A\) and \(B\) it is given that \(P (A)=0.3, P (B \mid A)=0.4\) and \(P \left(A^{\prime} \cap B^{\prime}\right)=0.15\). Find

(i) \(P (A \cup B)\),

[1]

(ii) \(P (B)\),

[3]

(iii) \(P \left(A \mid B^{\prime}\right)\).

[2]