Answer:
0.42
Step-by-step explanation:
Let the events be given as:
For twp mutually exclusive events, the probability of A1 is given as follows:
P (B1A1) = [tex]\frac{ P(B1) x P (BA1)}{P(A1)}[/tex]
       = 0.6
Solving the equation above  to get B1:
P (B1) = [tex]\frac{(0.8)x (0.6)}{(0.6)}[/tex]
     = 0.8
Therefore, computing P (A1B1) gives P(A1) × P (B1)
                             =  (0.8) × (0.6)
                             =  0.42 Ans