1. ## Probability mass function

The distribution of a random variable X is given by
$\displaystyle F(x) = \left\{ \begin{array}{lr} 0 & \text {if} \hspace {3pt} x <-2\\ \frac{1}{2} & \text {if} \hspace {3pt} -2 \leq x <2\\ \frac{3}{5} & \text {if} \hspace {3pt} 2 \leq x <4\\ \frac{8}{9} & \text {if} \hspace {3pt} 4 \leq x <6\\ 1 & \text {if} \hspace {3pt} x \geq 6\\ \end{array} \right$

Determine the probability mass function of X.

I have no idea where to begin. Can anyone show the process to determine the probability mass function so that I can repeat it for other problems?

2. Isn't this already a pmf?

3. Originally Posted by pickslides
$\displaystyle \begin{array}{*{20}c} \hline \vline & x &\vline & { - 2} &\vline & 2 &\vline & 4 &\vline & 6 & \\ \hline \vline & {f(x)} &\vline & {\frac{{45}} {{90}}} &\vline & {\frac{9} {{90}}} &\vline & {\frac{{26}} {{90}}} &\vline & {\frac{{10}} {{90}}} \\\end{array}$