6 The length, \(X\) centimetres, of worms of a certain type is modelled by the probability density function $$f ( x ) = \begin{cases} \frac { 6 } { 125 } ( 10 - x ) ( x - 5 ) & 5 \leqslant x \leqslant 10
0 & \text { otherwise } \end{cases}$$

1. State the value of \(\mathrm { E } ( X )\).
2. Find \(\operatorname { Var } ( X )\).
3. Two worms of this type are chosen at random. Find the probability that exactly one of them has length less than 6 cm .