Let A and B be two events such that $P(A) = 0.3 $ and $P(A ∪ B)=0.8$. If A and B are independent events, then P(B)=

$\frac{5}{6}$ $\frac{5}{7}$ $\frac{3}{5}$ $\frac{2}{5}$

$\frac{5}{7}$

Here $P(A ∪ B)=0.8, P(A) = 0.3 $ and A and B are independent events.  Let P(B) = x $∴ P(A ∪ B)= P(A) + P(B) - P(A ∩ B)⇒ P(A ∪ B)= P(A) +P(B) - P(A).P(B)$ $⇒ 0.8 = 0.3 + x - 0.3 x ⇒ x =\frac{5}{7}.$