Answer
$0.12\ mi$
Work Step by Step
Given radius of the track $r=2.7\ mi$ and the subtend angle $\theta=2^\circ30'=2.5^\circ$, the length of the train, which equals to the arc length, can be found as $L=r\theta=2.7\times2.5^\circ\times\frac{\pi}{180^\circ}\approx0.12\ mi$
