Fill in the blanks. a. P(A₁) P(B/A₁) + P(A₂) P(B|A₂) + P(A3) P(B/A3) = ___ b. P(A)=P(A/B₁). P(B₁) + ___ + P(A/B3) P(B3) + P(A/B4) P(B4)