JEE Advance - Mathematics (1994 - No. 7)

If two events $$A$$ and $$B$$ are such that $$P\,\,\left( {{A^c}} \right)\,\, = \,\,0.3,\,\,P\left( B \right) = 0.4$$ and $$P\left( {A \cap {B^c}} \right) = 0.5,$$ then $$P\left( {B/\left( {A \cup {B^c}} \right)} \right.$$$$\left. \, \right] = $$ ............