Question 1010401
The average speed of the train during those {{{"180.0 seconds"}}} is
{{{(12500meters/"180.0 seconds")(3600seconds/"1 hour")(1km/"1000 meters")="250.0 km / h"}}} .
Since the average uniformly increasing speed is the average of the initial and final speeds,
{{{Final}}}{{{speed=2("250.0 km / h")=highlight("500.0 km / h")}}} .