12. Suppose that A and B are two events such that $P(A) + P(B) < 1$. What is the
smallest possible value for $P(A \cap B)$?
Discrete random variable X the cumulative distribution function is given by
$F(x) = kx$, x=1, 2, 3.Use this information to answer questions 13-14.
13. Find the value of the constant k.
14. Find $P(X < 3)$.
15. A and B are two events such that $P(A) = \frac{2}{7}$ and $(A \cap B) = \frac{1}{5}$. If A and B are
independent, find $P(A \cup B)$.