A train goes past: Average velocity and acceleration (PhysCasts)

This PhysCast has a 1 dimensional motion problem with constant acceleration. You rush on to the train station platform, but your train is already leaving. You stop and watch as two of the 8.0 m train carriages move past you. The first one takes 1.6 s to go by and the next one takes 1.0s. Calculate the acceleration of the train, assuming it is constant