First convert speed from km/hr to m/sec
So, Speed = 72 × (5/18) = 20 m/sec
Time = 26 seconds
Let the length of the train be x meters.
We know, Distance = Speed × Time.
[you can remember this formula as remembering DUST = D × ST... Distance=Speed × Time]
x+250 = 20 × 26
=> x = 270 meters
So length of the goods train is 270 meter