Explanation:
Length of track = 1600 m
Average speed = 250 km/h = 69.44 m/s
We have
Distance = Speed x Time
1600 = 69.44 x time
Time = 23.04 seconds
Total time = 23.04 seconds
Half of the track = 0.5 x 1600 = 800 m
Speed on first half = 215 km/hr = 59.72 m/s
We have
Distance = Speed x Time
800 = 59.72 x time
Time = 13.40 seconds
Time taken to complete remaining half = 23.04 - 13.40 = 9.64 seconds
Distance = 800 m
We have
Distance = Speed x Time
800 = Speed x 9.64
Speed = 82.99 m/s = 298.76 km/hr
Its average speed (in km/h) on the second half is 298.76 km/hr