JEE Advance - Mathematics (1990 - No. 4)

Let $$A$$ and $$B$$ be two events such that $$P\,\,\left( A \right)\,\, = \,\,0.3$$ and $$P\left( {A \cup B} \right) = 0.8.$$ If $$A$$ and $$B$$ are independent events then $$P(B)=$$ ................