Alethia models the length of time, in minutes, by which her train is late on any day by the random variable $$\(X\)$$ with probability density function given by $$\( f(x)= \begin{cases}\frac{3}{8000}(x-20)^{2} & 0 \leqslant x \leqslant 20 \\ 0 & \text { otherwise. }\end{cases} \)$$ State one way in which Alethia's model may be unrealistic. ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................ ........................................................................................................................................................

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