6. The continuous random variable \(X\) has a probability density function
$$\mathrm { f } ( x ) = \left\{ \begin{array} { c c }
k ( x - 2 ) & 2 \leqslant x \leqslant 3
k & 3 < x < 5
k ( 6 - x ) & 5 \leqslant x \leqslant 6
0 & \text { otherwise }
\end{array} \right.$$
where \(k\) is a positive constant.
- Sketch the graph of \(\mathrm { f } ( x )\).
- Show that the value of \(k\) is \(\frac { 1 } { 3 }\)
- Define fully the cumulative distribution function \(\mathrm { F } ( x )\).
- Hence find the 90th percentile of the distribution.
- Find \(\mathrm { P } [ \mathrm { E } ( X ) < X < 5.5 ]\)
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