Suppose I have the following cdf of a random variable $X$.
$ F(x) = \begin{cases} 0 & \text{if } x < 0; \\ x/2 & \text{if } 0 \leq x < 1; \\ 2/3 & \text{if } 1 \leq x < 2; \\ 11/12 & \text{if } 2 \leq x < 3; \\ 1 & \text{if } x \geq 3.\end{cases} $
First, what is $\mathbb{P}(X<3)$? Is it $\frac{11}{12}$? Second, what is $\mathbb{P}(X=1)$? Is it $\frac{2}{3} - \frac{1}{2} = \frac{1}{6}$?