4 The error, \(X\) millimetres, made when the heights of prospective members of a new gym club are measured can be modelled by a rectangular distribution with the following probability density function. $$f ( x ) = \begin{cases} k & - 4 \leqslant x \leqslant 6
0 & \text { otherwise } \end{cases}$$

1. State the value of \(k\).
2. Write down the value of \(\mathrm { E } ( X )\).
3. Calculate \(\mathrm { P } ( X > 0 )\).
4. The height of a randomly selected prospective member is measured. Find the probability that the magnitude of the error made exceeds 3.5 millimetres.