8 The continuous random variable \(X\) has the cumulative distribution function
$$\mathrm { F } ( x ) = \left\{ \begin{array} { c c }
0 & x \leqslant - 4
\frac { x + 4 } { 9 } & - 4 \leqslant x \leqslant 5
1 & x \geqslant 5
\end{array} \right.$$
- Determine the probability density function, \(\mathrm { f } ( x )\), of \(X\).
- Sketch the graph of f .
- Determine \(\mathrm { P } ( X > 2 )\).
- Evaluate the mean and variance of \(X\).