3. The function \(\mathrm { f } ( x )\) is defined as
$$f ( x ) = \begin{cases} \frac { 1 } { 9 } ( x + 5 ) ( 3 - x ) & 1 \leqslant x \leqslant 4
0 & \text { otherwise } \end{cases}$$
Albert believes that \(\mathrm { f } ( x )\) is a valid probability density function.
- Sketch \(\mathrm { f } ( x )\) and comment on Albert's belief.
The continuous random variable \(Y\) has probability density function given by
$$g ( y ) = \begin{cases} k y \left( 12 - y ^ { 2 } \right) & 1 \leqslant y \leqslant 3
0 & \text { otherwise } \end{cases}$$
where \(k\) is a positive constant. - Use calculus to find the mode of \(Y\)
- Use algebraic integration to find the value of \(k\)
- Find the median of \(Y\) giving your answer to 3 significant figures.
- Describe the skewness of the distribution of \(Y\) giving a reason for your answer.